Information-signal recording and reproducing apparatus

This is a division of application Ser. No. 09/665,926, filed Sep. 20, 2000, now U.S. Pat. No. 6,285,632.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an information-signal recording apparatus and an information-signal reproducing apparatus. Also, this invention relates to an information-signal recording and reproducing apparatus. In addition, this invention relates to an information-signal communication apparatus. Furthermore, this invention relates to an information-signal recording medium.

2. Description of the Related Art

A typical optical-disc recorder/player operates as follows. During a recording mode of operation of the recorder/player, a signal representing at least one of video information and audio information is compressed into a compression-resultant information signal. An optical head in the recorder/player records the compression-resultant information signal on an optical disc. During a playback mode of operation of the recorder/player, the optical head reproduces a recorded signal from an optical disc. The reproduced signal is expanded into an original information signal.

It is known to provide such an optical-disc recorder/player with a buffer memory having a capacity of about 4 Mbits. A recorded signal is reproduced from an optical disc at a transfer rate of 10.08 Mbps. The reproduced signal is converted into an information signal having a variable transfer rate lower than 10.08 Mbps. The buffer memory absorbs the difference in transfer rate between the before-conversion signal and the after-conversion signal.

Japanese published unexamined patent application 10-92158 discloses a disc reproducing apparatus designed as follows. Discontinuation and disturbance of an image are prevented by dividing a cell into a plurality of cells, time-division-multiplexing the cells in each scene and arranging and recording the cells to be reproduced continuously within the distance of the particular amount of codes to shorten the physical moving distance during the reproducing operation. In Japanese application 10-92158, a video program has a preceding front trunk scene A, a plurality of branch scenes B<b>0</b> to B<b>3</b>, and a successive rear trunk scene C. In the case of recording a plurality of branch scenes on a recording medium, any branch scene is arranged in such a manner that a scene cell appears in the same rate for the summed total scene length. Arrangement should be done so that when the time for jumping the distance for the amount of particular codes is defined as Ts, the relationship Tc−[Tc×Pr/Rr]>Ts can be set for the amount of readout data Rr, amount of codes consumed Pr and image reproducing time Tc. When arrangement for recording is performed, a physical moving distance during the reproducing operation can be shortened and generation of discontinuation and disturbance of image can be prevented. The branch scenes B<b>0</b> to B<b>3</b> are multiple scenes. Each of the branch scenes B<b>0</b> to B<b>3</b> has a sequence of cells. The cells of the branch scenes B<b>0</b> to B<b>3</b> are shuffled before being recorded on a disc (a recording medium). Thus, the recorded cells of the branch scenes B<b>0</b> to B<b>3</b> are on non-successive separate positions on the disc. Accordingly, during the reproduction of the sequence of cells of one branch scene, a pickup head reproduces the cells and repetitively jumps between non-successive separate positions on the disc. In the apparatus of Japanese application 10-92158 includes a buffer memory capable of absorbing a time interval during which a pickup head jumps between non-successive separate positions on the disc so that reproduced data continue to be absent. Japanese application 10-92158 indicates the relation between the capacity of the buffer memory and a seek time of the pickup head which enables the buffer memory to continuously output data under conditions where the pickup head reproduces a sequence of cells of one branch scene and repetitively jumps between non-successive separate positions on the disc.

Japanese published unexamined patent application 6-139696 discloses a recording and reproducing apparatus which includes a buffer memory for absorbing a difference between transfer rates. In Japanese application 6-139696, during a recording mode of operation of the apparatus, first digital data having a lower transfer rate and being derived from an information signal to be recorded is converted into second digital data with a higher transfer rate. The second digital data are recorded on a disc at the higher transfer rate. During a playback mode of operation of the apparatus, third digital data are reproduced from the disc at the higher transfer rate, and the reproduced digital data are converted into fourth digital data related to the lower transfer rate. The fourth digital signal is converted into a reproduced information signal. The recording mode of operation and the playback mode of operation are implemented on a time sharing basis so that the information signal to be recorded and the reproduced information signal can simultaneously occur.

SUMMARY OF THE INVENTION

It is a first object of this invention to provide an improved information-signal recording apparatus.

It is a second object of this invention to provide an improved information-signal reproducing apparatus.

It is a third object of this invention to provide an improved information-signal recording and reproducing apparatus.

It is a fourth object of this invention to provide an improved information-signal communication apparatus.

It is a fifth object of this invention to provide an improved information-signal recording medium.

A first aspect of this invention provides an apparatus for reproducing information from a recording medium having first and second areas on which first and second information signals are recorded respectively, the first information signal having a size Ya, the second information signal having a size Yb. The apparatus comprises a head for reproducing the first and second information signals from the first and second areas of the recording medium and transmitting the reproduced first and second information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; and a buffer memory for receiving the first and second information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the first and second information signals, and for outputting the first and second information signals at first and second transfer rates Ra and Rb respectively, the first and second transfer rates Ra and Rb being lower than the predetermined constant transfer rate Rp; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A second aspect of this invention provides an apparatus for recording information on a recording medium having first and second areas. The apparatus comprises a buffer memory for receiving first and second information signals at first and second transfer rates Ra and Rb respectively, for temporarily storing the first and second information signals, and for outputting the first and second information signals at a predetermined constant transfer rate Rp higher than the first and second transfer rates Ra and Rb, the first information signal having a size Ya, the second information signal having a size Yb; and a head for receiving the first and second information signals from the buffer memory, and for recording the first and second information signals on the first and second areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A third aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas, the first area being loaded with a first information signal having a size Ya. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate Ra lower than the predetermined constant transfer rate Rp; the buffer memory being for receiving a second information signal at a second transfer rate Rb lower than the predetermined constant transfer rate Rp, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate Rp, the second information signal having a size Yb; the head being for receiving the second information signal from the buffer memory, and for recording the second information signal on the second area of the recording medium at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the second information signal on the second area of the recording medium on a time sharing basis while moving between the first and second areas of the recording medium; and wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A fourth aspect of this invention provides an apparatus for reproducing information from a recording medium having first and second areas on which first and second information signals are recorded respectively. The apparatus comprises a head for reproducing the first and second information signals from the first and second areas of the recording medium and transmitting the reproduced first and second information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; and a buffer memory for receiving the first and second information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the first and second information signals, and for outputting the first and second information signals at first and second transfer rates Ra and Rb respectively, the first and second transfer rates Ra and Rb being lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the capacity Ym of the buffer memory, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text><i>Ym</i>>{(<i>Rp−Ra</i>)·<i>Ra</i>+(<i>Rp−Rb</i>)·<i>Rb</i>}·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A fifth aspect of this invention provides an apparatus for recording information on a recording medium having first and second areas. The apparatus comprises a buffer memory for receiving first and second information signals at first and second transfer rates Ra and Rb respectively, for temporarily storing the first and second information signals, and for outputting the first and second information signals at a predetermined constant transfer rate Rp higher than the first and second transfer rates Ra and Rb, the buffer memory having a capacity Ym; and a head for receiving the first and second information signals from the buffer memory, and for recording the first and second information signals on the first and second areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the capacity Ym of the buffer memory, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text><i>Ym</i>>{(<i>Rp−Ra</i>)·<i>Ra</i>+(<i>Rp−Rb</i>)·<i>Rb</i>}·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A sixth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas, the first area being loaded with a first information signal. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate Ra lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; the buffer memory being for receiving a second information signal at a second transfer rate Rb lower than the predetermined constant transfer rate Rp, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate Rp; the head being for receiving the second information signal from the buffer memory, and for recording the second information signal on the second area of the recording medium at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the second information signal on the second area of the recording medium on a time sharing basis while moving between the first and second areas of the recording medium; and wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the capacity Ym of the buffer memory, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text><i>Ym</i>>{(<i>Rp−Ra</i>)·<i>Ra</i>+(<i>Rp−Rb</i>)·<i>Rb</i>}·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A seventh aspect of this invention is based on the first aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into first and second areas in accordance with values of the first and second transfer rates Ra and Rb, wherein the first and second areas in the buffer memory are assigned to the first and second information signals respectively.

An eighth aspect of this invention is based on the first aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into first and second areas in accordance with an operation mode, wherein the first and second areas in the buffer memory are assigned to the first and second information signals respectively.

A ninth aspect of this invention is based on the first aspect thereof, and provides an apparatus further comprising a first unit containing the head, and a second unit detachably connected with the first unit and containing the buffer memory.

A tenth aspect of this invention provides an apparatus comprising a head for reproducing an information signal from a recording medium and transmitting the reproduced information signal at a predetermined constant transfer rate; a buffer memory for receiving the information signal from the head at the predetermined constant transfer rate, for temporarily storing the information signal, and for outputting the information signal at a transfer rate lower than the predetermined constant transfer rate; a processor for receiving the information signal from the buffer memory and subjecting the information signal to a reproducing process; a first unit containing the head; and a second unit detachably connected with the first unit and containing the buffer memory and the processor.

An eleventh aspect of this invention provides an information-signal communication apparatus comprising the apparatus of the fist aspect of this invention and an interface connected with the buffer memory for communication with an external.

A twelfth aspect of this invention is based on the eleventh aspect thereof, and provides an information-signal communication apparatus further comprising a first unit containing the head, and a second unit detachably connected with the first unit and the interface and containing the buffer memory.

A thirteenth aspect of this invention provides an information-signal recording medium having first and second areas on which first and second information signals are recorded respectively, the first information signal having a size Ya, the second information signal having a size Yb, wherein the first and second information signals can be reproduced from the first and second areas and can be transmitted by a head on a time sharing basis and at a predetermined constant transfer rate Rp while the head moves between the first and second areas of the recording medium, wherein the first and second information signals outputted from the head can be received by a buffer memory at the predetermined constant transfer rate Rp and can be temporarily stored in the buffer memory before being outputted from the buffer memory at first and second transfer rates Ra and Rb respectively, the first and second transfer rates Ra and Rb being lower than the predetermined constant transfer rate Rp, wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A fourteenth aspect of this invention provides an apparatus for reproducing information from a recording medium having “n” areas on which “n” information signals are recorded respectively, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a head for reproducing the “n” information signals from the “n” areas of the recording medium and transmitting the reproduced “n” information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; and a buffer memory for receiving the “n” information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the “n” information signals, and for outputting the “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp; wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A fifteenth aspect of this invention provides an apparatus for recording information on a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, for temporarily storing the “n” information signals, and for outputting the “n” information signals at a predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn; and a head for receiving the “n” information signals from the buffer memory, and for recording the “n” information signals on the “n” areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A sixteenth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2, wherein at least a first area among the “n” areas is loaded with a first information signal among “n” information signals. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate R<b>1</b> lower than the predetermined constant transfer rate Rp; the buffer memory being for receiving the “n” information signals except the first information signal at transfer rates R<b>2</b>, R<b>3</b>, . . . , Rn respectively, for temporarily storing the “n” information signals except the first information signal, and for outputting the “n” information signals except the first information signal at the predetermined constant transfer rate Rp, the transfer rates R<b>2</b>, R<b>3</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp; the head being for receiving the “n” information signals except the first information signal from the buffer memory, and for recording the “n” information signals except the first information signal on the “n” areas of the recording medium except the first area at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the “n” information signals except the first information signal on the “n” areas of the recording medium except the first area on a time sharing basis while moving among the “n” areas of the recording medium; and wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A seventeenth aspect of this invention provides an apparatus for reproducing information from a recording medium having “n” areas on which “n” information signals are recorded respectively, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a head for reproducing the “n” information signals from the “n” areas of the recording medium and transmitting the reproduced “n” information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; and a buffer memory for receiving the “n” information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the “n” information signals, and for outputting the “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp; wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and an allowable seek time S taken by the head to move from present one to next one of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·n·S</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

An eighteenth aspect of this invention provides an apparatus for recording information on a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, for temporarily storing the “n” information signals, and for outputting the “n” information signals at a predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn; and a head for receiving the “n” information signals from the buffer memory, and for recording the “n” information signals on the “n” areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and an allowable seek time S taken by the head to move from present one to next one of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·n·S</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A nineteenth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2, wherein at least a first area among the “n” areas is loaded with a first information signal among “n” information signals. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate R<b>1</b> lower than the predetermined constant transfer rate Rp; the buffer memory being for receiving the “n” information signals except the first information signal at transfer rates R<b>2</b>, R<b>3</b>, . . . , Rn respectively, for temporarily storing the “n” information signals except the first information signal, and for outputting the “n” information signals except the first information signal at the predetermined constant transfer rate Rp, the transfer rates R<b>2</b>, R<b>3</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp; the head being for receiving the “n” information signals except the first information signal from the buffer memory, and for recording the “n” information signals except the first information signal on the “n” areas of the recording medium except the first area at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the “n” information signals except the first information signal on the “n” areas of the recording medium except the first area on a time sharing basis while moving among the “n” areas of the recording medium; and wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and an allowable seek time S taken by the head to move from present one to next one of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·n·S</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A twentieth aspect of this invention provides an apparatus for reproducing information from a recording medium having “n” areas on which “n” information signals are recorded respectively, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a head for reproducing the “n” information signals from the “n” areas of the recording medium and transmitting the reproduced “n” information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; and a buffer memory for receiving the “n” information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the “n” information signals, and for outputting the “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, the capacity Ym of the buffer memory, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text><i>Ym>Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A twenty-first aspect of this invention provides an apparatus for recording information on a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, for temporarily storing the “n” information signals, and for outputting the “n” information signals at a predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, the buffer memory having a capacity Ym; and a head for receiving the “n” information signals from the buffer memory, and for recording the “n” information signals on the “n” areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, the capacity Ym of the buffer memory, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text><i>Ym>Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A twenty-second aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2, wherein at least a first area among the “n” areas is loaded with a first information signal among “n” information signals. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate R<b>1</b> lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; the buffer memory being for receiving the “n” information signals except the first information signal at transfer rates R<b>2</b>, R<b>3</b>, . . . , Rn respectively, for temporarily storing the “n” information signals except the first information signal, and for outputting the “n” information signals except the first information signal at the predetermined constant transfer rate Rp, the transfer rates R<b>2</b>, R<b>3</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp; the head being for receiving the “n” information signals except the first information signal from the buffer memory, and for recording the “n” information signals except the first information signal on the “n” areas of the recording medium except the first area at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the “n” information signals except the first information signal on the “n” areas of the recording medium except the first area on a time sharing basis while moving among the “n” areas of the recording medium; and wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, the capacity Ym of the buffer memory, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text><i>Ym>Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A twenty-third aspect of this invention provides an apparatus for recording information on a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, for temporarily storing the “n” information signals, and for outputting the “n” information signals at a predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn; a head for receiving the “n” information signals from the buffer memory, and for recording the “n” information signals on the “n” areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; means for deciding whether or not parameters including the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

means for, in cases where it is decided that the parameters are in the relation, permitting the head to record the “n” information signals on the “n” areas of the recording medium respectively; means for, in cases where it is decided that the parameters are not in the relation, selecting “p” information signals from among the “n” information signals, where “p” denotes a predetermined natural number smaller than “n”; means for deciding whether or not the parameters are in the relation regarding the “p” information signals; and means for, in cases where it is decided that the parameters are in the relation regarding the “p” information signals, permitting the head to record the “p” information signals on “p” areas of the recording medium respectively, the “p” areas being among the “n” areas of the recording medium.

A twenty-fourth aspect of this invention provides an apparatus for recording information on a recording medium having “n” areas, where “n” denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, for temporarily storing the “n” information signals, and for outputting the “n” information signals at a predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn; a head for receiving the “n” information signals from the buffer memory, and for recording the “n” information signals on the “n” areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the “n” areas of the recording medium; means for deciding whether or not parameters including the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

means for, in cases where it is decided that the parameters are in the relation, permitting the head to record the “n” information signals on the “n” areas of the recording medium respectively; and means for, in cases where it is decided that the parameters are not in the relation, controlling the head to record the “n” information signals on a common area in the recording medium on a time sharing basis.

A twenty-fifth aspect of this invention is based on the twenty-fourth aspect thereof, and provides an apparatus further comprising means for rearranging the “n” information signals into “n” rearrangement-resultant information signals in the buffer memory, and for sequentially transmitting the “n” rearrangement-resultant information signals from the buffer memory to the head to sequentially record the “n” rearrangement-resultant signals.

A twenty-sixth aspect of this invention provides an apparatus for recording information on a recording medium. The apparatus comprises a buffer memory for receiving “n” information signals at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, for temporarily storing the “n” information signals, and for outputting the “n” information signals at a predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, where “n” denotes a predetermined natural number equal to or greater than 2; a head for receiving the “n” information signals from the buffer memory, and for recording the “n” information signals on the recording medium on a time sharing basis and at the predetermined constant transfer rate Rp; first means for causing the head to record the “n” information signals on at least two areas in the recording medium on a time sharing basis while moving the head among the areas in the recording medium under conditions where the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the areas in the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

second means for causing the head to record the “n” information signal on a common area in the recording medium on a time sharing basis; and third means for selecting and enabling one of the first and second means.

A twenty-seventh aspect of this invention is based on the twenty-sixth aspect thereof, and provides an apparatus wherein the third means comprises means for selecting and enabling one of the first and second means in response to one of types of the “n” information signals, users requirement, apparatus specifications, a type of the recording medium, and a condition of a usable area in the recording medium.

A twenty-eighth aspect of this invention is based on the fourteenth aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into “n” areas in accordance with values of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, wherein the “n” areas in the buffer memory are assigned to the “n” information signals respectively.

A twenty-ninth aspect of this invention is based on the fourteenth aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into “n” areas in accordance with an operation mode, wherein the “n” areas in the buffer memory are assigned to the “n” information signals respectively.

A thirtieth aspect of this invention provides an information-signal communication apparatus comprising the apparatus of the fourteenth aspect of this invention and an interface connected with the buffer memory for communication with an external.

A thirty-first aspect of this invention provides an information-signal recording medium having “n” areas on which “n” information signals are recorded respectively, where “n” denotes a predetermined natural number equal to or greater than 2, wherein the “n” information signals can be reproduced from the “n” areas and can be transmitted by a head on a time sharing basis and at a predetermined constant transfer rate Rp while the head moves among the “n” areas of the recording medium, wherein the “n” information signals outputted from the head can be received by a buffer memory at the predetermined constant transfer rate Rp and can be temporarily stored in the buffer memory before being outputted from the buffer memory at transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn respectively, the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn being lower than the predetermined constant transfer rate Rp, wherein the predetermined constant transfer rate Rp, a sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , Rn, a sum ΣYn of sizes of the “n” information signals, and a sum ΣSn of seek times taken by the head to move from present ones to next ones of the “n” areas of the recording medium are in a relation as follows:

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)</formula-text></maths>

A thirty-second aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas and a management area, the management area storing management information representing addresses in the first and second areas. The apparatus comprises a first buffer memory for receiving a first information signal at a first transfer rate, for temporarily storing the first information signal, and for outputting the first information signal at a predetermined constant transfer rate higher than the first transfer rate; a second buffer memory for receiving a second information signal at a second transfer rate lower than the predetermined constant transfer rate, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate; a head for receiving the first and second information signals from the first and second buffer memories and recording the first and second information signals on the first and second areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate while moving between the first and second areas of the recording medium; means for controlling the head to reproduce the management information from the management area of the recording medium before the head records the first and second information signals; means for deriving the addresses from the reproduced management information; means for searching for unoccupied regions in the first and second areas of the recording medium in response to the derived addresses; and means for deciding whether or not the first and second information signals can be recorded on the unoccupied regions while recording continuities related to the first and second information signals are maintained.

A thirty-third aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the first and second information signals can be recorded on the unoccupied regions while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A thirty-fourth aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the first and second information signals can be recorded on the unoccupied regions while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, and a maximum allowable seek time Tmax taken by the head to move on the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧2<i>·Rp</i>·(<i>Ra+Rb</i>)·<i>Tmax</i>/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A thirty-fifth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas and a management area, the first area being loaded with a first information signal, the management area storing management information representing addresses in the first and second areas. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate; a first buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate lower than the predetermined constant transfer rate; a second buffer memory for receiving a second information signal at a second transfer rate lower than the predetermined constant transfer rate, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate; the head being for receiving the second information signal from the second buffer memory, and for recording the second information signal on the second area of the recording medium at the predetermined constant transfer rate; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the second information signal on the second area of the recording medium on a time sharing basis while moving between the first and second areas of the recording medium; means for controlling the head to reproduce the management information from the management area of the recording medium before the head records the second information signal; means for deriving the addresses from the reproduced management information; means for searching for an unoccupied region in the second area of the recording medium in response to the derived addresses; and means for deciding whether or not the second information signal can be recorded on the unoccupied region while a recording continuity related to the second information signal is maintained.

A thirty-sixth aspect of this invention is based on the thirty-fifth aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the second information signal can be recorded on the unoccupied region while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A thirty-seventh aspect of this invention is based on the thirty-fifth aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the second information signal can be recorded on the unoccupied region while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, and a maximum allowable seek time Tmax taken by the head to move on the recording medium are in a relation as follows:

<maths><formula-text>(<i>Ya+Yb</i>)≧2<i>·Rp</i>·(<i>Ra+Rb</i>)·<i>Tmax</i>/(<i>Rp−Ra−Rb</i>)</formula-text></maths>

A thirty-eighth aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus further comprising means for indicating a result of the deciding by the deciding means.

A thirty-ninth aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus further comprising means for calculating a first total capacity of the unoccupied regions, means for calculating a second total capacity of usable portions of the unoccupied regions, means for calculating an recording efficiency equal to a ratio between the first total capacity and the second total capacity, and means for indicating the calculated recording efficiency.

According to the basic aspects of this invention, the signal transfer rate related to the recording and reproduction of information on and from a recording medium is preferably fixed to the predetermined constant transfer rate Rp.

Generally, this invention can operate on a recording medium such as a DVD-ROM, a DVD-RW, a DVD-RAM, a DVD+RW, and an HDD magnetic disc.

A DVD-ROM or a DVD-RW is subjected to CLV (constant linear velocity) control by a disc drive. Thus, the signal transfer rate is fixed throughout the whole area of the DVD-ROM or the DVD-RW.

A DVD-RAM is divided into zones. The DVD-RAM is subjected to zone CLV by a disc drive. The signal transfer rate varies from zone to zone by only several percent. This invention is adaptable to such a slightly-varying signal transfer rate.

Regarding a DVD+RW or an HDD magnetic disc, the signal transfer rate sometimes depends on a disc radial position. This invention can be applied to a disc area in which the signal transfer rate varies by several percent to several tens of percent.

In these case, it is preferable to calculate the signal transfer rate (Rp) regarding a recording medium as a minimum signal transfer rate which occurs when recording or reproduction is performed.

In this invention, information is recorded on and reproduced from two or more areas of a recording medium. The two or more areas of the recording medium may be a common area. In this case, this invention is designed to operate in one of the following modes. During a first mode of operation, first data are reproduced from an area of a recording medium and a portion of the reproduced first data is changed to form second data, and the second data are recorded on the same area of the recording medium. During a second mode of operation, data are recorded on an area of a recording medium, and then the data are reproduced therefrom and the reproduced data are analyzed to verify whether the data have been correctly recorded on the area of the recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an information-signal recording and reproducing apparatus according to a first embodiment of this invention.

FIG. 2 is a diagram of a portion of the apparatus in FIG. <b>1</b>.

FIG. 3 is a diagram of a portion of the apparatus in FIG. 1 which is operating in a two-signal playback mode.

FIG. 4 is a diagram of first areas in an optical disc.

FIG. 5 is a diagram of second areas in the optical disc.

FIG. 6 is a flowchart of a segment of a program for a system controller in FIG. 1 which relates to the two-signal playback mode of operation.

FIG. 7 is a time-domain diagram of the degrees of occupancy of first and second areas in a track buffer memory in FIG. 1 which occur in the two-signal playback mode of operation.

FIG. 8 is a diagram of a portion of the apparatus in FIG. 1 which is operating in a two-signal recording mode.

FIG. 9 is a flowchart of a segment of the program for the system controller in FIG. 1 which relates to the two-signal recording mode of operation.

FIG. 10 is a time-domain diagram of the degrees of occupancy of the first and second areas in the track buffer memory in FIG. 1 which occur in the two-signal recording mode of operation.

FIG. 11 is a diagram of a portion of the apparatus in FIG. 1 which is operating in a signal recording/playback mode.

FIG. 12 is a flowchart of a segment of the program for the system controller in FIG. 1 which relates to the signal recording/playback mode of operation.

FIG. 13 is a time-domain diagram of the degrees of occupancy of the first and second areas in the track buffer memory in FIG. 1 which occur in the signal recording/playback mode of operation.

FIG. 14 is a block diagram of an information-signal recording and reproducing apparatus according to a second embodiment of this invention.

FIG. 15 is a block diagram of an information-signal communication apparatus according to a third embodiment of this invention.

FIG. 16 is a block diagram of an inflation-signal communication apparatus according to a fourth embodiment of this invention.

FIG. 17 is a block diagram of an information-signal recording and reproducing apparatus according to a fifth embodiment of this invention.

FIG. 18 is a diagram of a portion of the apparatus in FIG. <b>17</b>.

FIG. 19 is a diagram of sub-areas in a first area of an optical disc.

FIG. 20 is a diagram of sub-areas in a second area of the optical disc.

FIG. 21 is a diagram of sub-areas in an n-th area of the optical disc.

FIG. 22 is a diagram of sub-areas in a management area of the optical disc.

FIG. 23 is a time-domain diagram of the degrees of occupancy of areas in a track buffer memory in FIG. 17 which occur in a multiple-signal playback mode of operation.

FIG. 24 is a time-domain diagram of the degrees of occupancy of the areas in the track buffer memory in FIG. 17 which occur in a multiple-signal recording mode of operation.

FIG. 25 is a block diagram of an information-signal communication apparatus according to a sixth embodiment of this invention.

FIG. 26 is a time-domain diagram of conditions of information signals which occur during a first recording procedure in a seventh embodiment of this invention.

FIG. 27 is a-time-domain diagram of conditions of information signals which occur during a second recording procedure in the seventh embodiment of this invention.

FIG. 28 is a time-domain diagram of conditions of information signals which occur during a third recording procedure in the seventh embodiment of this invention.

FIG. 29 is a time-domain diagram of conditions of information signals which occur during a fourth recording procedure in the seventh embodiment of this invention.

FIG. 30 is a block diagram of an information-signal recording and reproducing apparatus according to an eighth embodiment of this invention.

FIG. 31 is a diagram of a portion of the apparatus in FIG. <b>30</b>.

FIG. 32 is a diagram of sub-areas in a management area of an optical disc in FIG. <b>31</b>.

FIG. 33 is a diagram of a first example of indication on a display in FIG. <b>30</b>.

FIG. 34 is a diagram of a second example of indication on the display in FIG. <b>30</b>.

FIG. 35 is a diagram of a third example of indication on the display in FIG. <b>30</b>.

FIG. 36 is a flowchart of a segment of a program for a system controller in FIG. 30 which relates to a two-signal recording mode of operation.

FIG. 37 is a flowchart of a segment of the program for the system controller in FIG. 30 which relates to a signal recording/playback mode of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1 shows an information-signal recording and reproducing apparatus <b>10</b>A according to a first embodiment of this invention. The apparatus <b>10</b>A operates on an information-signal recording medium including an optical disc. Examples of the optical disc are a DVD-ROM, a DVD-RAM, a DVD-RW, and a DVD+RW. Alternatively, the information recording medium may include a magnetic disc such as a hard disc or a floppy disc. The information recording medium may include a semiconductor memory.

As shown in FIG. 1, the apparatus <b>10</b>A includes a spindle motor <b>11</b>, and a turntable <b>12</b> connected to the shaft of the spindle motor <b>11</b>. An optical disc (an information-signal recording medium) <b>13</b> can be placed on the turntable <b>12</b>. The apparatus <b>10</b>A further includes an optical head-(an optical pickup) <b>14</b>, a driver <b>15</b>, an amplifier unit <b>16</b>, a servo unit <b>17</b>, a signal processor <b>18</b>, a track buffer memory <b>19</b>, an audio-video encoding and decoding unit <b>20</b>, a memory <b>21</b>, a system controller <b>22</b>, a key input unit <b>23</b>, and an input/output terminal <b>24</b>.

When the optical disc <b>13</b> is placed on the turntable <b>12</b>, the spindle motor <b>11</b> rotates the turntable <b>12</b> and the optical disc <b>13</b>. In the case where the optical disc <b>13</b> is of a rewritable type, the optical head <b>14</b> writes and reads information thereon and therefrom. In the case where the optical disc <b>13</b> is designed exclusively for playback, the optical head <b>14</b> only reads information therefrom. The spindle motor <b>11</b> is connected to the driver <b>15</b> and the servo unit <b>17</b>. The optical head <b>14</b> is connected to the amplifier unit <b>16</b> and the driver <b>15</b>. The amplifier unit <b>16</b> is connected to the servo unit <b>17</b> and the signal processor <b>18</b>. The driver <b>15</b> is connected to the servo unit <b>17</b>. The signal processor <b>18</b> is connected to the track buffer memory <b>19</b> and the audio-video encoding and decoding unit <b>20</b>. The audio-video encoding and decoding unit <b>20</b> is connected to the memory <b>21</b> and the input/output terminal <b>24</b>. The system controller <b>22</b> is connected to the amplifier unit <b>16</b>, the servo unit <b>17</b>, the signal processor <b>18</b>, the audio-video encoding and decoding unit <b>20</b>, and the key input unit <b>23</b>.

The spindle motor <b>11</b> is driven and controlled by the driver <b>15</b>. The spindle motor <b>11</b> rotates the turntable <b>12</b> and the optical disc <b>13</b>. The spindle motor <b>11</b> is provided with an FG generator and a rotational position sensor (an angular position sensor). The rotational position sensor includes, for example, a Hall element. The FG generator outputs an FG signal (a rotational speed signal). The Hall element outputs a rotational position signal. The FG signal and the rotational position signal are fed back to the driver <b>15</b> and the servo unit <b>17</b> as rotation servo signals.

The optical head <b>14</b> faces the optical disc <b>13</b> placed on the turntable <b>12</b>. A feed motor (not shown) moves the optical head <b>14</b> radially with respect to the optical disc <b>13</b>. The feed motor is driven by the driver <b>15</b>. The optical head <b>14</b> includes a semiconductor laser, a collimator lens, and an objective lens. The semiconductor laser acts as a source for emitting a light beam (a laser beam). The emitted laser beam is focused into a laser spot on the optical disc <b>13</b> by the collimator lens and the objective lens. The optical head <b>14</b> includes a 2-axis actuator for driving the objective lens to implement focusing and tracking of the laser spot with respect to the optical disc <b>13</b>. The semiconductor laser is driven by a laser drive circuit in the optical head <b>14</b>. In the case where an information signal such as an audio signal or an audio-video signal is recorded, the information signal is subjected to waveform correction by a waveform correction circuit in the amplifier unit <b>16</b> before being fed to the laser drive circuit. The 2-axis actuator is driven by the driver <b>15</b>.

The key input unit <b>23</b> includes a plurality of keys which can be operated by a user. The key input unit <b>23</b> generates command signals in accordance with its operation by the user. The command signals are transmitted from the key input unit <b>23</b> to the system controller <b>22</b>. The command signals include a command signal for starting a recording mode of operation of the apparatus <b>10</b>A, and a command signal for starting a playback mode of operation of the apparatus <b>10</b>A. The key input unit <b>23</b> generates control data in accordance with its operation by the user. The control data are transmitted from the key input unit <b>23</b> to the system controller <b>22</b>.

The system controller <b>22</b> includes, for example, a microcomputer or a similar device which operates in accordance with a program stored in its internal ROM. The system controller <b>22</b> controls the amplifier unit <b>16</b>, the servo unit <b>17</b>, the signal processor <b>18</b>, and the audio-video encoding and decoding unit <b>20</b> in response to the command signals fed from the key input unit <b>23</b>.

Control data can be fed to the system controller <b>22</b> via an input terminal (not shown). The control data fed to the system controller <b>22</b> via the input terminal, and the control data fed to the system controller <b>22</b> from the key input unit <b>23</b> include a signal for adjusting the resolution of pictures represented by contents information to be recorded, a signal for separating quickly-moving scenes such as car racing scenes represented by contents information, and a signal for giving priority to a recording time. The system controller <b>22</b> changes an actual recording time in accordance with the control data. The system controller <b>22</b> enables the setting of the actual recording time to be selected by the user.

When the apparatus <b>10</b>A is required to start to operate in the playback mode, the key input unit <b>23</b> is actuated to generate the playback start command signal. The playback start command signal is transmitted from the key input unit <b>23</b> to the system controller <b>22</b>. The system controller <b>22</b> controls the amplifier unit <b>16</b> and the servo unit <b>17</b> in response to the playback start command signal, thereby starting the playback mode of operation of the apparatus <b>10</b>A. The control of the servo unit <b>17</b> includes steps of controlling the driver <b>15</b>. Firstly, the system controller <b>22</b> starts rotation of the optical disc <b>13</b> and application of a laser spot thereon through the control of the driver <b>15</b>. The optical head <b>14</b> is controlled by the driver <b>15</b>, thereby reading out address information from the optical disc <b>13</b>. For example, the address information is contained in management information stored in a management area of the optical disc <b>13</b>. The read-out address information is transmitted from the optical head <b>14</b> to the system controller <b>22</b> via the amplifier unit <b>16</b>. The system controller <b>22</b> finds or decides a target sector (a target track portion) to be played back by referring to the address information. The system controller <b>22</b> controls the optical head <b>14</b> via the servo unit <b>17</b>, the driver <b>15</b>, and the feed motor, thereby moving the optical head <b>14</b> radially with respect to the optical disc <b>13</b> and hence moving the laser spot to the target sector on the optical disc <b>13</b>. When the movement of the laser spot to the target sector is completed, the system controller <b>22</b> operates to start the reproduction of a signal from the target sector on the optical disc <b>13</b>. In this way, the playback mode of operation of the apparatus <b>10</b>A is started. During the playback mode of operation of the apparatus <b>10</b>A, the target sector is repetitively changed from one to another.

During the playback mode of operation of the apparatus <b>10</b>A, the optical head <b>14</b> scans the optical disc <b>13</b> and generates an RF signal containing information read out therefrom. A unit of generation of the RF signal corresponds to one correction block of the information recorded on the optical disc <b>13</b>. The optical head <b>14</b> outputs the RF signal to the amplifier unit <b>16</b>. The amplifier unit <b>16</b> enlarges the RF signal. In addition, the amplifier unit <b>16</b> generates a main reproduced signal, and tracking and focusing servo signals (tracking error and focusing error signals) from the enlarged RF signal. The amplifier unit <b>16</b> includes an equalizer for optimizing the frequency aspect of the main reproduced signal. Also, the amplifier unit <b>16</b> includes a PLL (phase locked loop) circuit for extracting a bit clock signal from the equalized main reproduced signal, and for generating a speed servo signal from the equalized main reproduced signal. Furthermore, the amplifier unit <b>16</b> includes a jitter generator for comparing the time bases of the bit clock signal and the equalized main reproduced signal, and for detecting jitter components from the results of the time-base comparison. A signal of the detected jitter components is transmitted from the amplifier unit <b>16</b> to the system controller <b>22</b>. The tracking and focusing servo signals and the speed servo signal are transmitted from the amplifier unit <b>16</b> to the servo unit <b>17</b>. The equalized main reproduced signal is transmitted from the amplifier unit <b>16</b> to the signal processor <b>18</b>.

The servo unit <b>17</b> receives the speed servo signal and the tracking and focusing servo signals from the amplifier unit <b>16</b>. The servo unit <b>17</b> receives the rotation servo signals from the spindle motor <b>11</b>. In response to these servo signals, the servo unit <b>17</b> implements corresponding servo control processes.

Specifically, the servo unit <b>17</b> generates a rotation control signal on the basis of the speed servo signal and the rotation servo signals. The rotation control signal is transmitted from the servo unit <b>17</b> to the spindle motor <b>11</b> via the driver <b>15</b>. The spindle motor <b>11</b> rotates at a speed depending on the rotation control signal. The rotation control signal is designed to rotate the optical disc <b>13</b> at a given constant linear velocity.

In addition, the servo unit <b>17</b> generates servo control signals on the basis of the focusing and tracking servo signals. The servo control signals are transmitted from the servo unit <b>17</b> to the 2-axis actuator in the optical head <b>14</b> via the driver <b>15</b>. The 2-axis actuator controls the laser spot on the optical disc <b>13</b> in response to the servo control signals, and thereby implements focusing and tracking of the laser spot with respect to the optical disc <b>13</b>.

During the playback mode of operation of the apparatus <b>10</b>A, the signal processor <b>18</b> receives the main reproduced signal from the amplifier unit <b>16</b>. The signal processor <b>18</b> is controlled by the system controller <b>22</b>, thereby converting the main reproduced signal into a corresponding reproduced digital signal. The signal processor <b>18</b> detects a sync signal from the reproduced digital signal. The signal processor <b>18</b> decodes an EFM+ signal (an 8-16 modulation signal) of the reproduced digital signal into NRZ data, that is, non-return-to-zero data. The signal processor <b>18</b> subjects the NRZ data to an error correction process for every correction block, thereby generating a sector address signal and first and second information signals. The sector address signal represents the address of a currently-accessed sector on the optical disc <b>13</b>. The sync signal and the sector address signal are fed from the signal processor <b>18</b> to the system controller <b>22</b>. It should be noted that the first and second information signals generated by the signal processor <b>18</b> correspond to first and second information signals resulting from compression at variable transfer rates (variable transmission rates) during a recording mode of operation.

During the playback mode of operation of the apparatus <b>10</b>A, the signal processor <b>18</b> temporarily stores the first and second information signals in the track buffer memory <b>19</b>. Thus, the signal processor <b>18</b> writes the first and second information signals into the track buffer memory <b>19</b>, and reads the first and second information signals therefrom. Writing and reading the first and second information signals into and from the track buffer memory <b>19</b> are controlled to absorb a time-domain change in the transfer rates of the first and second information signals. The track buffer memory <b>19</b> includes, for example, a D-RAM having a capacity of 64 Mbytes. The signal processor <b>18</b> outputs the read-out signal (the first and second information signals read out from the track buffer memory <b>19</b>) to the audio-video encoding and decoding unit <b>20</b>.

In the case where the first and second information signals fed from the track buffer memory <b>19</b> via the signal processor <b>18</b> are compressed MPEG2 data in which audio data and video data are multiplexed, the audio-video encoding and decoding unit <b>20</b> separates the first and second information signals into compressed audio data and compressed video data. The audio-video encoding and decoding unit <b>20</b> expands and decodes the compressed audio data into non-compressed audio data. In addition, the audio-vide encoding and decoding unit <b>20</b> expands and decodes the compressed video data into non-compressed video data. During the expansively decoding process, the audio-video encoding and decoding unit <b>20</b> temporarily stores signals and data in the memory <b>21</b>. The memory <b>21</b> includes, for example, a D-RAM having a capacity of 64 Mbytes. The audio-video encoding and decoding unit <b>20</b> converts the non-compressed audio data into a corresponding analog audio signal through digital-to-analog conversion. Also, the audio-video encoding and decoding unit <b>20</b> converts the non-compressed video data into a corresponding analog video signal through digital-to-analog conversion. It should be noted that the conversion of the non-compressed audio and video data into the analog audio and video signals may be implemented by digital-to-analog converters provided externally of the audio-video encoding and decoding unit <b>20</b>. The audio-video encoding and decoding unit <b>20</b> applies the analog audio signal and the analog video signal to the input/output terminal <b>24</b>. The analog audio signal and the analog video signal are transmitted to an external via the input/output terminal <b>24</b>.

The data rate of the expansively decoding process by the audio-video encoding and decoding unit <b>20</b>, that is, the data transfer rate (the data transmission rate) in the expansively decoding process, is equalized to an expansion data rate which is set in accordance with the type of the related recording mode of operation of the apparatus <b>10</b>A. Specifically, the audio-video encoding and decoding unit <b>20</b> can implement the expansively decoding process at a expansion data rate which can be changed among plural different expansion data rates. The audio-video encoding and decoding unit <b>20</b> selects one from among the plural different expansion data rates as a desired expansion data rate in accordance with the type of the related recording mode of operation of the apparatus <b>10</b>A. The audio-video encoding and decoding unit <b>20</b> executes the expansively encoding process at the desired expansion data rate. Information of the type of the recording mode of operation of the apparatus <b>10</b>A is recorded on the optical disc <b>13</b> as control data which may be contained in the management information. During an initial stage of the playback of the optical disc <b>13</b>, the control data are read out therefrom before being transmitted to the system controller <b>22</b>. The system controller <b>22</b> sets the expansion data rate in the audio-video encoding and decoding unit <b>20</b> in accordance with the control data.

When the apparatus <b>10</b>A is required to start to operate in the recording mode, the key input unit <b>23</b> is actuated to generate the recording start command signal. The recording start command signal is transmitted from the key input unit <b>23</b> to the system controller <b>22</b>. The system controller <b>22</b> controls the amplifier unit <b>16</b> and the servo unit <b>17</b> in response to the recording start command signal, thereby starting the recording mode of operation of the apparatus <b>10</b>A. The control of the servo unit <b>17</b> includes steps of controlling the driver <b>15</b>. Firstly, the system controller <b>22</b> starts rotation of the optical disc <b>13</b> and application of a laser spot thereon through the control of the driver <b>15</b>. The optical head <b>14</b> is controlled by the driver <b>15</b>, thereby reading out address information from the optical disc <b>13</b>. For example, the address information is contained in the management information stored in the management area of the optical disc <b>13</b>. The read-out address information is transmitted from the optical head <b>14</b> to the system controller <b>22</b> via the amplifier unit <b>16</b>. The system controller <b>22</b> finds or decides a target sector (a target track portion), on which a signal is to be recorded, by referring to the address information. The system controller <b>22</b> controls the optical head <b>14</b> via the servo unit <b>17</b>, the driver <b>15</b>, and the feed motor, thereby moving the optical head <b>14</b> radially with respect to the optical disc <b>13</b> and hence moving the laser spot to the target sector on the optical disc <b>13</b>. During the recording mode of operation of the apparatus <b>10</b>A, the target sector is repetitively changed from one to another.

During the recording mode of operation of the apparatus <b>10</b>A, an audio signal and a video signal to be recorded are fed via the input/output terminal <b>24</b> to the audio-video encoding and decoding unit <b>20</b>. The audio-video encoding and decoding unit <b>20</b> converts the audio signal into corresponding audio data through analog-to-digital conversion. In addition, the audio-video encoding and decoding unit <b>20</b> converts the video signal into corresponding video data through analog-to-digital conversion. It should be noted that the conversion of the audio and video signals into the audio and video data may be implemented by analog-to-digital converters provided externally of the audio-video encoding and decoding unit <b>20</b>. The audio-video encoding and decoding unit <b>20</b> compressively encodes the audio data and the video data into MPEG2 audio data and MPEG2 video data at a rate depending on the type of the recording mode. The audio-video encoding and decoding unit <b>20</b> multiplexes the MPEG2 audio data and the MPEG2 video data to form multiplexed MPEG2 data. The audio-video encoding and decoding unit <b>20</b> outputs the multiplexed MPEG2 data to the signal processor <b>18</b>. The data rate of the compressively encoding process by the audio-video encoding and decoding unit <b>20</b>, that is, the data transfer rate (the data transmission rate) in the compressively encoding process, is equalized to a compression data rate which is selected from among plural different rates in accordance with the type of the recording mode of operation of the apparatus <b>10</b>A. During the compressively encoding process, the audio-video encoding and decoding unit <b>20</b> temporarily stores data in the memory <b>21</b>.

It should be noted that the multiplexed MPEG2 data may be replaced by still-picture data or computer data such as program file data. In this case, the still-picture data or the computer data are transmitted to the system controller <b>22</b> via an interface (not shown). The system controller <b>22</b> transfers the still-picture data or the computer data to the signal processor <b>18</b>.

During the recording mode of operation of the apparatus <b>10</b>A, the signal processor <b>18</b> adds error correction code signals (ECC signals) to the multiplexed MPEG2 data, the still-picture data, or the computer data. The signal processor <b>18</b> subjects the ECC-added data to NRZ and EFM+ encoding processes. The signal processor <b>18</b> adds a sync signal to the encoding-resultant data to form sync-added data. The sync signal is fed from the system controller <b>22</b>. The sync-added data are temporarily stored in the track buffer memory <b>19</b>. The sync-added data are read out from the track buffer memory <b>19</b> at a data rate corresponding to a data rate of signal recording on the optical disc <b>13</b>. The signal processor <b>18</b> subjects the read-out data to given modulation for record. The signal processor <b>18</b> outputs the modulation-resultant signal to the amplifier unit <b>16</b>. The amplifier unit <b>16</b> corrects the waveform of the output signal of the signal processor <b>18</b>. The amplifier unit <b>16</b> outputs the waveform-correction-resultant signal to the laser drive circuit in the optical head <b>14</b>. The optical head <b>14</b> records the output signal of the amplifier unit <b>16</b> on the target sector (the target track portion) on the optical disc <b>13</b>.

The amplifier unit <b>16</b> informs the system controller <b>22</b> of detected jitter components. The system controller <b>22</b> subjects the detected jitter components to analog-to-digital conversion to generate a measured jitter value. During the recording mode of operation of the apparatus <b>10</b>A, the system controller <b>22</b> adjusts the degree or characteristic of the waveform correction by the amplifier unit <b>16</b> in response to the measured jitter value and an asymmetry value.

Operation of the apparatus <b>10</b>A can be changed among various modes. During a first mode of operation which corresponds to the previously-mentioned playback mode of operation, the apparatus <b>10</b>A reproduces an audio signal (audio signals) or an audio-video signal (audio-video signals) from the optical disc <b>13</b>. During a second mode of operation which corresponds to the previously-mentioned recording mode of operation, the apparatus <b>10</b>A records an audio signal or an audio-video signal on the optical disc <b>13</b>. During a third mode of operation, the apparatus <b>10</b>A records an audio signal or an audio-video signal on one area of the optical disc <b>13</b> while reproducing an audio signal or an audio-video signal from another area of the optical disc <b>13</b>. During a fourth mode of operation, the apparatus <b>10</b>A reproduces an audio signal or an audio-video signal from one area of the optical disc <b>13</b> while recording an audio signal or an audio-video signal on another area of the optical disc <b>13</b>. During a fifth mode of operation, the apparatus <b>10</b>A reproduces an audio signal or an audio-video signal from one area of the optical disc <b>13</b> while reproducing an audio signal or an audio-video signal from another area of the optical disc <b>13</b>. During a sixth mode of operation, the apparatus <b>10</b>A records an audio signal or an audio-video signal on one area of the optical disc <b>13</b> while recording an audio signal or an audio-video signal on another area of the optical disc <b>13</b>. These various modes of operation of the apparatus <b>10</b>A meet user's requests for the implementation of an after-recording process and a different-channel-program recording process.

The apparatus <b>10</b>A can record first and second information signals on different areas of the optical disc <b>13</b>, respectively, on a time sharing basis. The first and second information signals are first and second audio-video information signals respectively. Alternatively, the first and second information signals may be first and second audio information signals respectively. The apparatus <b>10</b>A can record only one of the first and second information signals on the optical disc <b>13</b>.

The apparatus <b>10</b>A can reproduce first and second information signals from different areas of the optical disc <b>13</b>, respectively, on a time sharing basis. The first and second information signals are first and second audio-video information signals respectively. Alternatively, the first and second information signals may be first and second audio information signals respectively. The apparatus <b>10</b>A can reproduce only one of the first and second information signals from the optical disc <b>13</b>.

FIG. 2 shows a portion of the apparatus <b>10</b>A. The amplifier unit <b>16</b> and the signal processor <b>18</b> are omitted from FIG. 2 for a better understanding. As shown in FIG. 2, the optical disc <b>13</b> has first areas <b>13</b><i>a </i>assigned to a first information signal “A”, and second areas <b>13</b><i>b </i>assigned to a second information signal “B”. The first areas <b>13</b><i>a </i>have equal sizes, and are separate from each other. The second areas <b>13</b><i>b </i>have equal sizes, and are separate from each other. The second areas <b>13</b><i>b </i>are separate from the first areas <b>13</b><i>a</i>. The first information signal “A” is divided into blocks each having a predetermined size (a predetermined total number of bits) Ya. The predetermined size Ya is a unit (a unit capacity) for continuous reproduction (or continuous recording) of information, or a unit (a unit capacity) for reproduction (or recording) of continuous information. The first areas <b>13</b><i>a </i>are allocated to the blocks of the first information signal “A”, respectively. The second information signal “B” is divided into blocks each having a predetermined size (a predetermined total number of bits) Yb equal to or different from the predetermined size Ya. The predetermined size Yb is a unit (a unit capacity) for continuous reproduction (or continuous recording) of information, or a unit (a unit capacity) for reproduction (or recording) of continuous information. The second areas <b>13</b><i>b </i>are allocated to the blocks of the second information signal “B”, respectively. The first information signal “A” and the second information signal “B” are related or unrelated to each other. Each of the first and second information signals “A” and “B” represents audio data, video data, audio-video data, or computer data.

The track buffer memory <b>19</b> has a first area <b>19</b><i>a </i>assigned to the first information signal “A”, and a second area <b>19</b><i>b </i>assigned to the second information signal “B”.

With reference to FIG. 2, the optical head <b>14</b> transfers the first information signal “A” and the second information signal “B” between the optical disc <b>13</b> and the track buffer memory <b>19</b> on a time sharing basis and at a predetermined constant transfer rate Rp. The predetermined constant transfer rate Rp is equal to, for example, 25 Mbps.

The first information signal “A” is transferred between the track buffer memory <b>19</b> and the audio-video encoding and decoding unit <b>20</b> at a transfer rate Ra selected from among predetermined values. All the predetermined values are lower than the predetermined constant transfer rate Rp related to the optical head <b>14</b>. The second information signal “B” is transferred between the track buffer memory <b>19</b> and the audio-video encoding and decoding unit <b>20</b> at a transfer rate Rb changeable among the predetermined values.

As will be mentioned later, the apparatus <b>10</b>A can substantially continuously and simultaneously record or reproduce the first information signal “A” and the second information signal “B”.

In more detail, each of the transfer rates Ra and Rb is selected from among a value of 8 Mbps which corresponds to a recording time of 2 hours and a high picture quality, a value of 4 Mbps which corresponds to a recording time of 4 hours and a slightly high picture quality, and a value of 2 Mbps which corresponds to a recording time of 8 hours and a normal picture quality. Ones of these values can be designated as desired values of the transfer rates Ra and Rb according to user's operation of the key input unit <b>23</b> (see FIG. <b>1</b>). A value of 17 Mbps may be added to the candidate values. During the recording of the first information signal “A” and the second information signal “B” on the optical disc <b>13</b>, the transfer rates Ra and Rb are set to the desired values designated by user's operation of the key input unit <b>23</b>. During the reproduction of the first information signal “A” and the second information signal “B” from the optical disc <b>13</b>, information of recording compression rates is derived from control data for the information signals “A” and “B”, and the transfer rates Ra and Rb are set in response to the recording compression rates. Alternatively, during the reproduction of the first information signal “A” and the second information signal “B” from the optical disc <b>13</b>, control data (management information) representative of transfer rates Ra and Rb used in the recording are reproduced from the optical disc <b>13</b>, and the reproduction transfer rates Ra and Rb are set in accordance with the reproduced control data.

The system controller <b>22</b> (see FIG. 1) controls the track buffer memory <b>19</b> via the signal processor <b>18</b> (see FIG. <b>1</b>). The system controller <b>22</b> virtually divides or partitions the track buffer memory <b>19</b> into the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b</i>. Specifically, the system controller <b>22</b> sets the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>in the track buffer memory <b>19</b> in response to the values of the transfer rates Ra and Rb. The ratio in capacity between the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>depends on the ratio “Ra:Rb”, that is, the ratio between the transfer rates Ra and Rb. Regarding the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b>, the system controller <b>22</b> sets an empty value and a full value in response to the value of the transfer rate Ra. The empty value corresponds to a slightly occupied state or a substantially empty state of the first area <b>19</b><i>a. </i>The full value corresponds to a fully occupied state of the first area <b>19</b><i>a. </i>Regarding the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b>, the system controller <b>22</b> sets an empty value and a full value in response to the value of the transfer rate Rb. The empty value corresponds to a slightly occupied state or a substantially empty state of the second area <b>19</b><i>b</i>.The full value corresponds to a fully occupied state of the second area <b>19</b><i>b</i>.The system controller <b>22</b> always monitors the degree of occupancy of each of the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>which varies between the related empty value and the related full value under normal conditions.

Alternatively, the division of the track buffer memory <b>19</b> into the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>may be responsive to the type of the mode of operation of the apparatus <b>10</b>A. For example, in the case of the operation mode during which the apparatus <b>10</b>A reproduces one of the information signals “A” and “B” and records the other information signal, greater one of the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>is assigned to the information signal to be recorded while smaller one is assigned to the reproduced information signal. This design reliably prevents the occurrence of an interruption of the continuously recording of the information signal. The system controller <b>22</b> implements the division of the track buffer memory <b>19</b> into the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>when receiving a recording start command signal or a playback start command signal. Preferably, the system controller <b>22</b> implements the division of the track buffer memory <b>19</b> after confirming the absence of data from the track buffer memory <b>19</b> which are being reproduced or recorded.

Two-Signal Playback Mode

FIG. 3 shows a portion of the apparatus <b>10</b>A which is operating in a two-signal playback mode. The amplifier unit <b>16</b> and the signal processor <b>18</b> are omitted from FIG. 3 for a better understanding. With reference to FIG. 3, the optical disc <b>13</b> is designed exclusively for playback. The optical disc <b>13</b> has the first areas <b>13</b><i>a </i>on which the blocks of the first information signal “A” are previously recorded respectively. In addition, the optical disc <b>13</b> has the second areas <b>13</b><i>b </i>on which the blocks of the second information signal “B” are previously recorded respectively. Each of the blocks of the first information signal “A” has a predetermined size (a predetermined total number of bits) Ya. Each of the blocks of the second information signal “B” has a predetermined size (a predetermined total number of bits) Yb equal to or different from the predetermined size Ya.

As shown in FIG. 4, the first areas <b>13</b><i>a </i>of the optical disc <b>13</b> are given addresses A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively. Thus, the first areas <b>13</b><i>a </i>are also referred to as the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The blocks of the first information signal “A” are recorded on the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively. Preferably, the size Ya of the blocks of the first information signal “A” is equal to the size of the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The placement of the first areas <b>13</b><i>a </i>is designed to meet requirements for a seek time. As shown in FIG. 5, the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> are given addresses B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . respectively. Thus, the second areas <b>13</b><i>b </i>are also referred to as the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The blocks of the second information signal “B” are recorded on the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively. Preferably, the size Yb of the blocks of the second information signal “B” is equal to the size of the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The placement of the second areas <b>13</b><i>b </i>is designed to meet requirements for a seek time. First, a block of the first information signal “A” is reproduced from first one A<b>1</b> (the first area <b>13</b><i>a </i>a given the address A<b>1</b>) of the first areas <b>13</b><i>a</i>. Second, a block of the second information signal “B” is reproduced from first one B<b>1</b> (the second area <b>13</b><i>b </i>given the address B<b>1</b>) of the second areas <b>13</b><i>b. </i>The first area A<b>1</b> and the second area B<b>1</b> are located relative to each other so that the optical head <b>14</b> can move therebetween in a predetermined time (equal to, for example, 1.5 seconds). Therefore, the maximum seek time during which the optical head <b>14</b> moves between the first area <b>13</b><i>a </i>and the second area <b>13</b><i>b </i>is equal to the predetermined time (for example, 1.5 seconds).

During the two-signal playback mode of operation of the apparatus <b>10</b>A, the optical head <b>14</b> moves to a position of a designated track on the optical disc <b>13</b> and waits for a start sector. Then, the optical head <b>14</b> meets the start sector, and the reproduction of the first information signal “A” and the second information signal “B” is started. The system controller <b>22</b> derives information of recording compression rates (information of transfer rates Ra and Rb) from control data for the reproduced information signals “A” and “B”. The system controller <b>22</b> divides or partitions the track buffer memory <b>19</b> into a first area <b>19</b><i>a </i>and a second area <b>19</b><i>b, </i>and sets capacities of the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>in response to the recording compression rates. In addition, the system controller <b>22</b> sets empty values and full values of the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>in response to the recording compression rates.

The optical head <b>14</b> alternately reproduces the first information signal “A” and the second information signal “B” from the first areas <b>13</b><i>a </i>and the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> on a time sharing basis. The reproduced first information signal “A”, is stored into the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> from the optical head <b>14</b> at a predetermined constant transfer rate Rp (equal to, for example, 25 Mbps). The reproduced second information signal “B” is stored into the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> from the optical head <b>14</b> at the predetermined constant transfer rate Rp. Storing the reproduced first information signal “A” into the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> alternates with storing the reproduced second information signal “B” into the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b>.

The system controller <b>22</b> sets transfer rates Ra and Rb for the first information signal “A” and the second information signal “B” on the basis of the recording compression rates. The transfer rates Ra and Rb are lower than the predetermined constant transfer rate Rp. The first information signal “A” is transmitted from the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra. The second information signal “B” is transmitted from the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. Generally, the transmission of the first information signal “A” from the track buffer memory <b>19</b> and the transmission of the second information signal “B” from the track buffer memory <b>19</b> are implemented on a time sharing basis. The audio-video encoding and decoding unit <b>20</b> expands and decodes the first information signal “A” into a first non-compressed information signal “A”. In addition, the audio-video encoding and decoding unit <b>20</b> expands and decodes the second information signal “B” into a second non-compressed information signal “B”. The first non-compressed information signal “A” and the second non-compressed information signal “B” are transmitted from the audio-video encoding and decoding unit <b>20</b> to a display and a loudspeaker, being simultaneously converted into corresponding pictures and sounds.

The system controller <b>22</b> operates in accordance with a program stored in its internal ROM. FIG. 6 is a flowchart of a segment of the program which relates to the two-signal playback mode of operation of the apparatus <b>10</b>A. The program segment in FIG. 6 is started in response to a two-signal-playback start command signal fed from the key input unit <b>23</b>.

With reference to FIG. 6, a first step S<b>32</b> of the program segment decides whether or not the optical head <b>14</b> has reached a target position on the optical disc <b>13</b>. Initially, the target position corresponds to first one A<b>1</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. When the optical head <b>14</b> has not reached the target position yet, the step S<b>32</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>32</b> to a step S<b>33</b>.

The step S<b>33</b> enables the optical head <b>14</b> to reproduce the first information signal “A” from the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>. The step S<b>33</b> stores the reproduced first information signal “A” into the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp.

A step S<b>34</b> following the step S<b>33</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>34</b> to the step S<b>33</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>34</b> to a step S<b>35</b>.

The step S<b>35</b> transfers the first information signal “A” from the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra.

A step S<b>36</b> following the step S<b>35</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>36</b> to the step S<b>35</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>36</b> to a step S<b>37</b>.

The step S<b>37</b> forces the optical head <b>14</b> to suspend the reproduction of the first information signal “A” from the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>.

A step S<b>38</b> subsequent to the step S<b>37</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, first one B<b>1</b> of the second areas <b>13</b><i>b </i>in the optical disc <b>13</b>. After the step S<b>38</b>, the program advances to a step S<b>39</b>.

The step S<b>39</b> decides whether or not the optical head <b>14</b> has reached the target position on the optical disc <b>13</b>. When the optical head <b>14</b> has not reached the target position yet, the step S<b>39</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>39</b> to a step S<b>40</b>.

In this way, the optical head <b>14</b> moves from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b </i>in the optical disc <b>13</b>. The seek time Tab related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

The step S<b>40</b> enables the optical head <b>14</b> to reproduce the second information signal “B” from the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>. The step S<b>40</b> stores the reproduced second information signal “B” into the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp.

A step S<b>41</b> following the step S<b>40</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>41</b> to the step S<b>40</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>41</b> to a step S<b>42</b>.

The step S<b>42</b> transfers the second information signal “B” from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb.

A step S<b>43</b> following the step S<b>42</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>43</b> to the step S<b>42</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>43</b> to a step S<b>44</b>.

The step S<b>44</b> forces the optical head <b>14</b> to suspend the reproduction of the second information signal “B” from the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>.

A step S<b>45</b> subsequent to the step S<b>44</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, second one A<b>2</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. After the step S<b>45</b>, the program returns to the step S<b>32</b>.

Thus, the optical head <b>14</b> moves from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a </i>in the optical disc <b>13</b>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

During the repetitive execution of the program segment in FIG. 6, the target position of the optical head <b>14</b> is sequentially set into correspondence with the first and second areas A<b>1</b>, B<b>1</b>, A<b>2</b>, B<b>2</b>, A<b>3</b>, B<b>3</b>, . . . in the optical disc <b>13</b>. Therefore, the optical head <b>14</b> alternately reproduces the first information signal “A” and the second information signal “B” from the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b> in the order as “A1, B1, A2, B2, A3, B3, . . . ”.

Preferably, the step S<b>37</b> or the step S<b>44</b> is followed by a step which decides whether or not both the reproduction of the first information signal “A” from the optical disc <b>13</b> and the reproduction of the second information signal “B” therefrom are required to be suspended. In this case, when both the reproduction of the first information signal “A” from the optical disc <b>13</b> and the reproduction of the second information signal “B” therefrom are required to be suspended, the optical head <b>14</b> is controlled to implement the required suspension of reproduction.

With reference to FIG. 7, after the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> reaches the related empty value, the first information signal “A” is read out from the memory area <b>19</b><i>a </i>at the transfer rate Ra and the first information signal “A” is transmitted from the first area A<b>1</b> in the optical disc <b>13</b> to the memory area <b>19</b><i>a </i>at the predetermined constant transfer rate Rp. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>a </i>increases at a rate corresponding to “Rp−Ra”.

When the degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related full value, the transmission of the first information signal “A” from the first area A<b>1</b> in the optical disc <b>13</b> to the memory area <b>19</b><i>a </i>is suspended. Then, the optical head <b>14</b> is moved to a position corresponding to the second area B<b>1</b> in the optical disc <b>13</b>. The seek time Tab related to this movement of the optical head <b>14</b> is equal to or shorter than 1.5 seconds. The optical head <b>14</b> transmits the second information signal “B” from the second area B<b>1</b> in the optical disc <b>13</b> to the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp. Even after the degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related full value, the first information signal “A” continues to be read out from the memory area <b>19</b><i>a </i>at the transfer rate Ra. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>a </i>decreases at a rate corresponding to “Ra”. The read-out of the first information signal “A” from the memory area <b>19</b><i>a </i>is completed before the optical head <b>14</b> accesses the first area A<b>2</b> in the optical disc <b>13</b>.

After the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> reaches the related empty value, the second information signal “B” is read out from the memory area <b>19</b><i>b </i>at the transfer rate Rb and the second information signal “B” continues to be transmitted from the second area B<b>1</b> in the optical disc <b>13</b> to the memory area <b>19</b><i>b </i>at the predetermined constant transfer rate Rp. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>b </i>increases at a rate corresponding to “Rp−Rb”.

When the degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related full value, the transmission of the second information signal “B” from the second area B<b>1</b> in the optical disc <b>13</b> to the memory area <b>19</b><i>b </i>is suspended. Then, the optical head <b>14</b> is moved to a position corresponding to the first area A<b>2</b> in the optical disc <b>13</b>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to or shorter than 1.5 seconds. The optical head <b>14</b> transmits the first information signal “A” from the first area A<b>2</b> in the optical disc <b>13</b> to the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp. Even after the degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related full value, the second information signal “B” continues to be read out from the memory area <b>19</b><i>b </i>at the transfer rate Rb. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>b </i>decreases at a rate corresponding to “Rb”. The read-out of the second information signal “B” from the memory area <b>19</b><i>b </i>is completed before the optical head <b>14</b> accesses the second area B<b>2</b> in the optical disc <b>13</b>.

As previously indicated, the rate of the transfer of the first and second information signals “A” and “B” by the optical head <b>14</b> is denoted by “Rp” (Mbps). The rate of the transfer of the first information signal “A” from the track buffer memory <b>19</b> is denoted by “Ra” (Mbps). The rate of the transfer of the second information signal “B” from the track buffer memory <b>19</b> is denoted by “Rb” (Mbps). The minimum capacity of the track buffer memory <b>19</b> is denoted by “Ym” (Mbits). The size (the total number of bits) of the first information signal “A” recorded on each of the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . in the optical disc <b>13</b> is denoted by “Ya” (Mbits). The size (the total number of bits) of the second information signal “B” recorded on each of the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . in the optical disc <b>13</b> is denoted by “Yb” (Mbits). The seek time of movement of the optical head <b>14</b> from a first area <b>13</b><i>a </i>to a second area <b>13</b><i>b </i>in the optical disc <b>13</b> is denoted by “Tab” (s). The seek time of movement of the optical head <b>14</b> from a second area <b>13</b><i>b </i>to a first area <b>13</b><i>a </i>in the optical disc <b>13</b> is denoted by “Tba” (s).

The seek time Tab is equal to a first time interval plus a second time interval. The first time interval starts from the moment at which the optical head <b>14</b> reaches a reproduction end position and suspends the reproduction of the first information signal “A” from the first area <b>13</b><i>a </i>of the optical disc <b>13</b>. The first time interval ends and the second time interval starts when the optical head <b>14</b> moves to the second area <b>13</b><i>b </i>of the optical disc <b>13</b>. The second time interval continues until the optical head <b>14</b> starts reproducing the second information signal “B” from the second area <b>13</b><i>b </i>of the optical disc <b>13</b>. During the second time interval, a target address of the second area <b>13</b><i>b </i>of the optical disc <b>13</b> is found, and preparations for the reproduction of the second information signal “B” therefrom have been made.

Similarly, the seek time Tba is equal to a first time interval plus a second time interval. The first time interval starts from the moment at which the optical head <b>14</b> reaches a reproduction end position and suspends the reproduction of the second information signal “B” from the second area <b>13</b><i>b </i>of the optical disc <b>13</b>. The first time interval ends and the second time interval starts when the optical head <b>14</b> moves to the first area <b>13</b><i>a </i>of the optical disc <b>13</b>. The second time interval continues until the optical head <b>14</b> starts reproducing the first information signal “A” from the first area <b>13</b><i>a </i>of the optical disc <b>13</b>. During the second time interval, a target address of the first area <b>13</b><i>a </i>of the optical disc <b>13</b> is found, and preparations for the reproduction of the first information signal “A” therefrom have been made.

The mean value of the rate Ra of the transfer of the first information signal “A” from the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> plus the mean value of the rate Rb of the transfer of the second information signal “B” from the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> equals smaller than the rate Rp of the transfer of the first and second information signals “A” and “B” to the track buffer memory <b>19</b>. Thus, the transfer rates Rp, Ra, and Rb are in the following relation.

<maths><formula-text><i>Rp>Ra+Rb</i>  (1)</formula-text></maths>

The playback time Ta (S) for which the optical head <b>14</b> continuously reproduces the first information signal “A” from the optical disc <b>13</b> is given as follows.

<maths><formula-text><i>Ta=Ya/Rp</i>  (2)</formula-text></maths>

The playback time Tb (S) for which the optical head <b>14</b> continuously reproduces the second information signal “B” from the optical disc <b>13</b> is given as follows.

<maths><formula-text><i>Tb=Yb/Rp</i>  (3)</formula-text></maths>

Regarding the transfer rates Rp, Ra, and Rb, the following ratio is considered.

<maths><formula-text><i>Rp</i>/(<i>Rp−Ra−Rb</i>)  (4)</formula-text></maths>

where “Rp” corresponds to a 1-cycle time during which the first and second information signals “A” and “B” are sequentially reproduced once, and “(Rp−Ra−Rb)” corresponds to a seek period in the 1-cycle time.

Regarding the times Ta, Tab, Th, and Tba, the following ratio is considered.

<maths><formula-text>(<i>Ta+Tab+Tb+Tba</i>)/(<i>Tab+Tba</i>)  (5)</formula-text></maths>

where “(Ta+Tab+Tb+Tba)” corresponds to a 1-cycle time during which the first and second information signals “A” and “B” are sequentially reproduced once, and “(Tab+Tba)” corresponds to a total seek period in the 1-cycle time.

The ratio in the relation (4) and the ratio in the relation (5) are equal to each other, and the following equation is available.

<maths><formula-text><i>Rp</i>/(<i>Rp−Ra−Rb</i>)=(<i>Ta+Tab+Tb+Tba</i>)/(<i>Tab+Tba</i>)  (6)</formula-text></maths>

The equation (6) is changed into the following version.

<maths><formula-text>(<i>Ta+Tb</i>)=(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (7)</formula-text></maths>

Combining the equations (2) and (3) with the equation (7) results in the following equation.

<maths><formula-text>(<i>Ya+Yb</i>)=<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (8)</formula-text></maths>

The rate Rp of the transfer of the first and second information signals “A” and “B” from the optical disc <b>13</b> to the track buffer memory <b>19</b> is equal to the predetermined constant value. The rates Ra and Rb of the transfer of the first and second information signals “A” and “B” from the track buffer memory <b>19</b> are decided on the basis of the conditions of recording the first and second information signals “A” and “B” on the optical disc <b>13</b>. The seek times Tab and Tba are decided according to the specifications of the apparatus <b>10</b>A and the addresses on the optical disc <b>13</b>. To implement continuous playback regarding both the first and second information signals “A” and “B”, the size (the total number of bits) Ya of the first information signal “A” on each of the first areas <b>13</b><i>a </i>of the optical disc <b>13</b> and the size (the total number of bits) Yb of the second information signal “B” on each of the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> are chosen to satisfy relations (9), (10), and (11) as follows.

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (9)</formula-text></maths>

<maths><formula-text><i>Ya≧Rp·Ra</i>·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (10)</formula-text></maths>

<maths><formula-text><i>Yb≧Rp·Rb</i>·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (11)</formula-text></maths>

During the two-signal playback mode of operation of the apparatus <b>10</b>A, the first information signal “A” is continuously transferred from one of the first areas <b>13</b><i>a </i>of the optical disc <b>13</b> to the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> before the second information signal “B” is continuously transferred from one of the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> to the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b>. The first and second information signals “A” and “B” are continuously transferred from the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>of the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b>. To enable the audio-video encoding and decoding unit <b>20</b> to continuously recover the contents of the first and second information signals “A” and “B”, the size (the total number of bits) Ya of the first information signal “A” on each of the first areas <b>13</b><i>a </i>of the optical disc <b>13</b> and the size (the total number of bits) Yb of the second information signal “B” on each of the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> are chosen to satisfy the above-indicated relations (9), (10), and (11) while the relation among the transfer rates Ra and Rb and the seek times Tab and Tba is taken into consideration.

In addition, the maximum size of the track buffer memory <b>19</b>, and the empty value and the full value related to each of the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>in the track buffer memory <b>19</b> are decided according to the relations (9), (10), and (11).

The minimum capacity Ym of the track buffer memory <b>19</b> satisfies one of the following relations (12) and (13).

<maths><formula-text><i>Ym</i>>(<i>Tb+Tab+Tba</i>)·<i>Ra</i>+(<i>Ta+Tab+Tba</i>)·<i>Rb</i>  (12)</formula-text></maths>

<maths><formula-text><i>Ym>Ta</i>·(<i>Rp−Ra</i>)+<i>Tb</i>·(<i>Rp−Rb</i>)  (13)</formula-text></maths>

Combining the equations and relations (2), (3), (10), and (11) with the relations (12) and (13) result in the following relation.

<maths><formula-text><i>Ym</i>>{(<i>Rp−Ra</i>)·<i>Ra</i>+(<i>Rp−Rb</i>)·<i>Rb</i>}·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (14)</formula-text></maths>

The term “(Rp−Ra)·Ra·(Tab+Tba)/(Rp−Ra−Rb)” in the relation (14) means a first memory-size reference value for the first information signal “A”. Similarly, the term “(Rp−Rb)·Rb·(Tab+Tba)/(Rp−Ra−Rb)” in the relation (14) means a second memory-size reference value for the second information signal “B”. According to the relation (14), it is preferable that the size of the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> for the first information signal “A” is set greater than the first memory-size reference value, and that the related empty value and the related full value are decided in view of the setting of the size of the first memory area <b>19</b><i>a</i>. Similarly, it is preferable that the size of the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> for the second information signal “B” is set greater than the second memory-size reference value, and that the related empty value and the related full value are decided in view of the setting of the size of the second memory area <b>19</b><i>b. </i>

To provide a small margin for more reliably implementing continuous playback of the contents of the first and second information signals “A” and “B”, the minimum capacity Ym of the track buffer memory <b>19</b> satisfies the following relation.

<maths><formula-text><i>Ym</i>>(<i>Ta+Tb+Tab+Tba</i>)·(<i>Ra+Rb</i>)  (15)</formula-text></maths>

In the case where the seek times Tab and Tba are set to a same fixed value T, the relation (15) is rewritten as follows.

<maths><formula-text><i>Ym</i>>(<i>Ta+Tb+</i>2<i>T</i>)·(<i>Ra+Rb</i>)  (16)</formula-text></maths>

To provide a system margin for allowing a retry process and a shock-proof memory function, it is preferable that the minimum capacity Ym of the track buffer memory <b>19</b> exceeds the value defined by the right-hand side of the relation (16).

Accordingly, it is more preferable that the size of the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> for the first information signal “A” is set greater than the value “(Ta+Tb+2T)·Ra”, and that the related empty value and the related full value are decided in view of the setting of the size of the first memory area <b>19</b><i>a</i>. Similarly, it is more preferable that the size of the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> for the second information signal “B” is set greater than the value “(Ta+Tb+2T)·Rb”, and that the related empty value and the related full value are decided in view of the setting of the size of the second memory area <b>19</b><i>b. </i>

Combining the equations (2) and (3) and the relation (9) with the relation (15) results in the following relation.

<maths><formula-text><i>Ym>Rp</i>·(<i>Ra+Rb</i>)·(<i>Tab+Tba</i>)/(<i>Rp−Ra−Rb</i>)  (17)</formula-text></maths>

In the case where the seek times Tab and Tba are set to the same fixed value T, the relation (17) is rewritten as follows.

<maths><formula-text><i>Ym></i>2<i>·Rp</i>·(<i>Ra+Rb</i>)·<i>T</i>/(<i>Rp−Ra−Rb</i>)  (18)</formula-text></maths>

To provide a system margin for allowing a retry process and a shock-proof memory function, it is preferable that the minimum capacity Ym of the track buffer memory <b>19</b> exceeds the value defined by the right-hand side of the relation (18).

Accordingly it is more preferable that the size of the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> for the first information signal “A” is set greater than the value “Rp·Ra·(Tab+Tba)/(Rp−Ra−Rb)”, and that the related empty value and the related full value are decided in view of the setting of the size of the first memory area <b>19</b><i>a</i>. Similarly, it is more preferable that the size of the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> for the second information signal “B” is set greater than the value “Rp·Rb·(Tab+Tba)/(Rp−Ra−Rb)”, and that the related empty value and the related full value are decided in view of the setting of the size of the second memory area <b>19</b><i>b. </i>

It should be noted that a portion of the buffer memory <b>21</b> connected to the audio-video encoding and decoding unit <b>20</b> may be used as a track buffer memory substituting for the track buffer memory <b>19</b>.

The track buffer memory <b>19</b> absorbs the differences between the predetermined constant transfer rate Rp and the transfer rates Ra and Rb, that is, the differences between the reproduced-signal transfer rate determined by the optical head <b>14</b> and the transfer rates related to the expansion-resultant information signals (the expansion-resultant audio-video signals). In a preferable way, two basic areas for the first information signal “A” and the second information signal “B” are provided in the track buffer memory <b>19</b>, and the remaining area of the track buffer memory <b>19</b> is divided into two portions assigned to the first information signal “A” and the second information signal “B” respectively. The division-resultant two portions are referred to as additive areas. One basic area plus one additive area are assigned to the first information signal “A”. Similarly, one basic area plus one additive area are assigned to the second information signal “B”. The ratio in size between the additive areas is substantially equal to that between the basic areas. The additive areas provide margins to track buffers for the first and second information signals “A” and “B”, respectively.

For example, the first area <b>19</b><i>a </i>and the second area <b>19</b><i>b </i>are provided in the track buffer memory <b>19</b> as follows. In the case where the transfer rate Ra for the first information signal “A” is set to 8 Mbps, a first basic area of 32 Mbits for the first information signal “A” is provided in the track buffer memory <b>19</b>. In the case where the transfer rate Rb for the second information signal “B” is set to 4 Mbps, a second basic area of 16 Mbits for the second information signal “B” is provided in the track buffer memory <b>19</b>. The remaining 16-Mbit area of the track buffer memory <b>19</b> is divided into a first portion (a first additive area) of about 10 Mbits and a second portion (a second additive area) of about 5 Mbits. The first basic area and the first additive area are combined into the first memory area <b>19</b><i>a </i>for the first information signal “A”. The first memory area <b>19</b><i>a </i>has a size of about 42 Mbits. The second basic area and the second additive area are combined into the second memory area <b>19</b><i>b </i>for the second information signal “B”. The second memory area <b>19</b><i>b </i>has a size of about 21 Mbits. This memory division enables the track buffer memory <b>19</b> to be efficiently used.

The system controller <b>22</b> provides the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>in the track buffer memory <b>19</b> in response to the two-signal-playback start command signal and the information of the transfer rates Ra and Rb. During a one-signal playback mode of operation of the apparatus <b>10</b>A, the track buffer memory <b>19</b> is used as a non-partitioned 64-Mbit memory. Thus, during the one-signal playback mode of operation of the apparatus <b>10</b>A, the playability including the retry performance can be enhanced. Preferably, the system controller <b>22</b> checks data in the track buffer memory <b>19</b> when receiving the two-signal-playback start command signal. The system controller <b>22</b> implements the division of the track buffer memory <b>19</b> into the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>after confirming the absence of data from the track buffer memory <b>19</b> which are being reproduced or recorded. During the two-signal playback mode of operation of the apparatus <b>10</b>A, when the transfer rates Ra and Rb for the information signals “A” and “B” are changed, the system controller <b>22</b> checks data in the track buffer memory <b>19</b>. In this case, the system controller <b>22</b> redivides the track buffer memory <b>19</b> after confirming the absence of data from the track buffer memory <b>19</b> which are being reproduced or recorded. Thus, the margins of the track buffer memory <b>19</b> remains optimized even when the transfer rates Ra and Rb for the information signals “A” and “B” are changed.

Preferably, the maximum values Tmax of the seek times Tab and Tba related to the optical head <b>14</b> are equal to each other. The maximum seek time Tmax is equal to, for example, 1.5 seconds. When the maximum seek time Tmax is used for the seek times Tab and Tba, the previously-indicated relation (9) is changed into the following version.

<maths><formula-text>(<i>Ya+Yb</i>)≧<i>Rp</i>·(<i>Ra+Rb</i>)·2<i>·Tmax</i>/(<i>Rp−Ra−Rb</i>)  (19)</formula-text></maths>

When the maximum seek time Tmax is equal to 1.5 seconds, the relation (19) is rewritten as follows.

<maths><formula-text>(<i>Ya+Yb</i>)≧3<i>·Rp</i>·(<i>Ra+Rb</i>)/(<i>Rp−Ra−Rb</i>)  (20)</formula-text></maths>

Preferably, the size (the total number of bits) Ya of the first information signal “A” on each of the first areas <b>13</b><i>a </i>of the optical disc <b>13</b> and the size (the total number of bits) Yb of the second information signal “B” on each of the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> are chosen to satisfy the relation (19) or (20).

Two-Signal Recording Mode

FIG. 8 shows a portion of the apparatus <b>10</b>A which is operating in a two-signal recording mode. The amplifier unit <b>16</b> and the signal processor <b>18</b> are omitted from FIG. 8 for a better understanding. With reference to FIG. 8, the first information signal “A” is transmitted from the audio-video encoding and decoding unit <b>20</b> to the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> at the first transfer rate Ra. The second information signal “B” is transmitted from the audio-video encoding and decoding unit <b>20</b> to the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the second transfer rate Rb. Generally, the transmission of the first information signal “A” to the track buffer memory <b>19</b> and the transmission of the second information signal “B” to the track buffer memory <b>19</b> are implemented on a time sharing basis. The first information signal “A” is transmitted from the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The second information signal “B” is transmitted from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The optical head <b>14</b> records the first information signal “A” and the second information signal “B” on the first area <b>13</b><i>a </i>and the second area <b>13</b><i>b </i>of the optical disc <b>13</b> respectively on a time sharing basis and at the predetermined constant transfer rate Rp. The predetermined constant transfer rate Rp is higher than the first and second transfer rates Ra and Rb.

The optical disc <b>13</b> is of the rewritable type. The optical disc <b>13</b> is previously provided with the first areas <b>13</b><i>a </i>for storing the respective blocks of the first information signal “A”. In addition, the optical disc <b>13</b> is previously provided with the second areas <b>13</b><i>b </i>for storing the respective blocks of the second information signal “B”. The second areas <b>13</b><i>b </i>are separate from the first areas <b>13</b><i>a. </i>

The first areas <b>13</b><i>a </i>in the optical disc <b>13</b> are given addresses A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively (see FIG. <b>4</b>). Thus, the first areas <b>13</b><i>a </i>are also referred to as the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The blocks of the first information signal “A” are recorded on the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively. Preferably, the size Ya of the blocks of the first information signal “A” is equal to the size of the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The placement of the first areas <b>13</b><i>a </i>is designed to meet requirements for a seek time. The second areas <b>13</b><i>b </i>in the optical disc <b>13</b> are given addresses B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively (see FIG. <b>5</b>). Thus, the second areas <b>13</b><i>b </i>are also referred to as the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The blocks of the second information signal “B” are recorded on the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively. Preferably, the size Yb of the blocks of the second information signal “B” is equal to the size of the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The placement of the second areas <b>13</b><i>b </i>is designed to meet the requirements for a seek time. First, a block of the first information signal “A” is recorded on the first area A<b>1</b> (the first area <b>13</b><i>a </i>given the address A<b>1</b>). Second, a block of the second information signal “B” is recorded on the second area B<b>1</b> (the second area <b>13</b><i>b </i>given the address B<b>1</b>). The first area A<b>1</b> and the second area B<b>1</b> are located relative to each other so that the optical head <b>14</b> can move therebetween in a predetermined time (equal to, for example, 1.5 seconds). Therefore, the maximum seek time during which the optical head <b>14</b> moves between the first area <b>13</b><i>a </i>and the second area <b>13</b><i>b </i>is equal to the predetermined time (for example, 1.5 seconds).

During the two-signal recording mode of operation of the apparatus <b>10</b>A, the audio-video encoding and decoding unit <b>20</b> encodes original information signals into the first and second information signals “A” and “B” respectively. The first and second information signals “A” and “B” are transferred from the audio-video encoding and decoding unit <b>20</b> to the track buffer memory <b>19</b> at the rates Ra and Rb respectively. The rates Ra and Rb of the transfer of the first and second information signals “A” and “B” from the audio-video encoding and decoding unit <b>20</b> to the track buffer memory <b>19</b> can be selected from among different values according to user's operation of the key input unit <b>23</b> (see FIG. <b>1</b>). The different values include a transfer rate of 8 Mbps which corresponds to a recording time of 2 hours and a high picture quality, a transfer rate of 4 Mbps which corresponds to a recording time of 4 hours and a slightly high picture quality, and a transfer rate of 2 Mbps which corresponds to a recording time of 8 hours and a normal picture quality. A transfer rate of 17 Mbps may be added to the candidate values. The first and second information signals “A” and “B” are temporarily stored in the first and second areas <b>19</b><i>a </i>and <b>19</b><i>b </i>of the track buffer memory <b>19</b>. At an initial stage, the optical head <b>14</b> is in a stand-by state or a kick wait state while being located at a position corresponding to a target track on the optical disc <b>13</b>. The system controller <b>22</b> always monitors the degree of occupancy of each of the first and second memory areas <b>19</b><i>a </i>and <b>19</b><i>b </i>which varies between the related empty value and the related full value under normal conditions. When the degrees of occupancy of the first and second memory areas <b>19</b><i>a </i>and <b>19</b><i>b </i>reach the related full values, the first and second information signals “A” and “B” start to be alternately read out from the first and second memory areas <b>19</b><i>a </i>and <b>19</b><i>b </i>on a time sharing basis and at the predetermined constant transfer rate Rp. The optical head <b>14</b> alternately records the read-out first information signal “A” and the read-out second information signal “B” on the first areas <b>13</b><i>a </i>and the second areas <b>13</b><i>b </i>of the optical disc <b>13</b> respectively on a time sharing basis and at the predetermined constant transfer rate Rp. In this way, the continuously and simultaneously recording of the original information signals is implemented.

The system controller <b>22</b> operates in accordance with the program stored in its internal ROM. FIG. 9 is a flowchart of a segment of the program which relates to the two-signal recording mode of operation of the apparatus <b>10</b>A. The program segment in FIG. 9 is started in response to a two-signal-recording start command signal fed from the key input unit <b>23</b>.

With reference to FIG. 9, a first step S<b>52</b> of the program segment decides whether or not the optical head <b>14</b> has reached a target position on the optical disc <b>13</b>. Initially, the target position corresponds to first one A<b>1</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. When the optical head <b>14</b> has not reached the target position yet, the step S<b>52</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>52</b> to a step S<b>53</b>.

The step S<b>53</b> stores the first information signal “A”, which is outputted from the audio-video encoding and decoding unit <b>20</b>, into the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> at the transfer rate Ra.

A step S<b>54</b> following the step S<b>53</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>54</b> to the step S<b>53</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>54</b> to a step S<b>55</b>.

The step S<b>55</b> transfers the first information signal “A” from the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The step S<b>55</b> enables the optical head <b>14</b> to record the first information signal “A” on the present first area <b>13</b><i>a </i>in the optical disc <b>13</b> at the predetermined constant transfer rate Rp.

A step S<b>56</b> following the step S<b>55</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>56</b> to the step S<b>55</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>56</b> to a step S<b>57</b>.

The step S<b>57</b> forces the optical head <b>14</b> to suspend the recording of the first information signal “A” on the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>.

A step S<b>58</b> subsequent to the step S<b>57</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, first one B<b>1</b> of the second areas <b>13</b><i>b </i>in the optical disc <b>13</b>. After the step S<b>58</b>, the program advances to a step S<b>59</b>.

The step S<b>59</b> decides whether or not the optical head <b>14</b> has reached the target position on the optical disc <b>13</b>. When the optical head <b>14</b> has not reached the target position yet, the step S<b>59</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>59</b> to a step S<b>60</b>.

In this way, the optical head <b>14</b> moves from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b </i>in the optical disc <b>13</b>. The seek time Tab related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

The step S<b>60</b> stores the second information signal “B”, which is outputted from the audio-video encoding and decoding unit <b>20</b>, into the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the transfer rate Rb.

A step S<b>61</b> following the step S<b>60</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>61</b> to the step S<b>60</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>61</b> to a step S<b>62</b>.

The step S<b>62</b> transfers the second information signal “B” from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The step S<b>62</b> enables the optical head <b>14</b> to record the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b> at the predetermined constant transfer rate Rp.

A step S<b>63</b> following the step S<b>62</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>63</b> to the step S<b>62</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>63</b> to a step S<b>64</b>.

The step S<b>64</b> forces the optical head <b>14</b> to suspend the recording of the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>.

A step S<b>65</b> subsequent to the step S<b>64</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, second one A<b>2</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. After the step S<b>65</b>, the program returns to the step S<b>52</b>.

Thus, the optical head <b>14</b> moves from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a </i>in the optical disc <b>13</b>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

During the repetitive execution of the program segment in FIG. 9, the target position of the optical head <b>14</b> is sequentially set into correspondence with the first and second areas A<b>1</b>, B<b>1</b>, A<b>2</b>, B<b>2</b>, A<b>3</b>, B<b>3</b>, . . . in the optical disc <b>13</b>. Therefore, the optical head <b>14</b> alternately records the first information signal “A” and the second information signal “B” on the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b> in the order as “A1, B1, A2, B2, A3, B3, . . . ”.

Preferably, the step S<b>57</b> or the step S<b>64</b> is followed by a step which decides whether or not both the recording of the first information signal “A” on the optical disc <b>13</b> and the recording of the second information signal “B” thereon are required to be suspended. In this case, when both the recording of the first information signal “A” on the optical disc <b>13</b> and the recording of the second information signal “B” thereon are required to be suspended, the optical head <b>14</b> is controlled to implement the required suspension of recording.

It is preferable to provide the optical disc <b>13</b> with a management area separate from the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b. </i>For example, the management area extends in an innermost portion of the optical disc <b>13</b>. After the recording of the first and second information signals “A” and “B” on the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>in the optical disc <b>13</b> has been completed, address information of the blocks of the first and second information signals “A” and “B” on the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>is recorded on the management area in the optical disc <b>13</b>. Information of the first and second transfer rates Ra and Rb may also be recorded on the management area in the optical disc <b>13</b>.

With reference to FIG. 10, after the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> reaches the related full value, the first information signal “A” is transmitted from the memory area <b>19</b><i>a </i>to the first area A<b>1</b> in the optical disc <b>13</b> at the predetermined constant transfer rate Rp and the first information signal “A” is stored into the memory area <b>19</b><i>a </i>from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>a </i>decreases at a rate corresponding to “Rp−Ra”.

When the degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related empty value, the transmission of the first information signal “A” from the memory area <b>19</b><i>a </i>to the first area A<b>1</b> in the optical disc <b>13</b> is suspended. Then, the optical head <b>14</b> is moved to a position corresponding to the second area B<b>1</b> in the optical disc <b>13</b>. The seek time Tab related to this movement of the optical head <b>14</b> is equal to or shorter than 1.5 seconds. The second information signal “B” is stored into the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. Even after the degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related empty value, the first information signal “A” continues to be stored into the memory area <b>19</b><i>a </i>from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>a </i>increases at a rate corresponding to “Ra”. The degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related full value before the optical head <b>14</b> accesses the first area A<b>2</b> in the optical disc <b>13</b>.

After the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> reaches the related full value, the second information signal “B” is transmitted from the memory area <b>19</b><i>b </i>to the second area B<b>1</b> in the optical disc <b>13</b> at the predetermined constant transfer rate Rp and the second information signal “B” continues to be stored into the memory area <b>19</b><i>b </i>from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>b </i>decreases at a rate corresponding to “Rp−Rb”.

When the degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related empty value, the transmission of the second information signal “B” from the memory area <b>19</b><i>b </i>to the second area B<b>1</b> in the optical disc <b>13</b> is suspended. Then, the optical head <b>14</b> is moved to a position corresponding to the first area A<b>2</b> in the optical disc <b>13</b>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to or shorter than 1.5 seconds. Even after the degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related empty value, the second information signal “B” continues to be stored into the memory area <b>19</b><i>b </i>from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>b </i>increases at a rate corresponding to “Rb”. The degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related full value before the optical head <b>14</b> accesses the second area B<b>2</b> in the optical disc <b>13</b>.

Preferably, the transfer rate Ra, the transfer rate Rb, the size Ya of each block of the first information signal “A” on one first area <b>13</b><i>a </i>in the optical disc <b>13</b>, the size Yb of each block of the second information signal “B” on one second area <b>13</b><i>b </i>in the optical disc <b>13</b>, the seek time Tab related to the movement of the optical head <b>14</b> from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b </i>of the optical disc <b>13</b>, the seek time Tba related to the movement of the optical head <b>14</b> from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a </i>of the optical disc <b>13</b>, and the minimum capacity Ym of the track buffer memory <b>19</b> are chosen to satisfy the previously-indicated relations (1)-(18).

Signal Recording/Playback Mode

FIG. 11 shows a portion of the apparatus <b>10</b>A which is operating in a signal recording/playback mode. The amplifier unit <b>16</b> and the signal processor <b>18</b> are omitted from FIG. 11 for a better understanding. With reference to FIG. 11, the optical head <b>14</b> reproduces the first information signal “A” from the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. The first information signal “A” is transmitted from the optical head <b>14</b> to the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp. The first information signal “A” is transmitted from the first area <b>19</b><i>a </i>of the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the first transfer rate Ra. On the other hand, the second information signal “B” is transmitted from the audio-video encoding and decoding unit <b>20</b> to the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the second transfer rate Rb. The second information signal “B” is transmitted from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The optical head <b>14</b> records the second information signal “B” on the second areas <b>13</b><i>b </i>in the optical disc <b>13</b>. The optical head <b>14</b> alternately accesses the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b> on a time sharing basis so that the playback of the contents of the first information signal “A” and the recording of the contents of the second information signal “B” can be virtually simultaneously implemented.

The optical disc <b>13</b> is of the rewritable type. The optical disc <b>13</b> is previously provided with the first areas <b>13</b><i>a </i>for storing the first information signal “A”. In addition, the optical disc <b>13</b> is previously provided with the second areas <b>13</b><i>b </i>for storing the second information signal “B”. The second areas <b>13</b><i>b </i>are separate from the first areas <b>13</b><i>a. </i>

The first areas <b>13</b><i>a </i>in the optical disc <b>13</b> are given addresses A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively (see FIG. <b>4</b>). Thus, the first areas <b>13</b><i>a </i>are also referred to as the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The blocks of the first information signal “A” are recorded on the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively. Preferably, the size Ya of the blocks of the first information signal “A” is equal to the size of the first areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The placement of the first areas <b>13</b><i>a </i>is designed to meet requirements for a seek time. The second areas <b>13</b><i>b </i>in the optical disc <b>13</b> are given addresses B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively (see FIG. <b>5</b>). Thus, the second areas <b>13</b><i>b </i>are also referred to as the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The blocks of the second information signal “B” are recorded on the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively. Preferably, the size Yb of the blocks of the second information signal “B” is equal to the size of the second areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The placement of the second areas <b>13</b><i>b </i>is designed to meet the requirements for a seek time. First, a block of the information signal “A” is reproduced from the first area A<b>1</b> (the first area <b>13</b><i>a </i>given the address A<b>1</b>). Second, a block of the information signal “B” is recorded on the second area B<b>1</b> (the second area <b>13</b><i>b </i>given the address B<b>1</b>). The first area A<b>1</b> and the second area B<b>1</b> are located relative to each other so that the optical head <b>14</b> can move therebetween in a predetermined time (equal to, for example, 1.5 seconds). Therefore, the maximum seek time during which the optical head <b>14</b> moves between the first area <b>13</b><i>a </i>and the second area <b>13</b><i>b </i>is equal to the predetermined time (for example, 1.5 seconds).

The system controller <b>22</b> operates in accordance with the program stored in its internal ROM. FIG. 12 is a flowchart of a segment of the program which relates to the signal recording/playback mode of operation of the apparatus <b>10</b>A. The program segment in FIG. 12 is started in response to a signal-recording/playback start command signal fed from the key input unit <b>23</b>.

With reference to FIG. 12, a first step S<b>72</b> of the program segment decides whether or not the optical head <b>14</b> has reached a target position on the optical disc <b>13</b>. Initially, the target position corresponds to first one A<b>1</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. When the optical head <b>14</b> has not reached the target position yet, the step S<b>72</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>72</b> to a step S<b>73</b>.

The step S<b>73</b> enables the optical head <b>14</b> to reproduce the first information signal “A” from the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>. The step S<b>73</b> stores the reproduced first information signal “A” into the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp.

A step S<b>74</b> following the step S<b>73</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>74</b> to the step S<b>73</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>74</b> to a step S<b>75</b>.

The step S<b>75</b> transfers the first information signal “A” from the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra.

A step S<b>76</b> following the step S<b>75</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>76</b> to the step S<b>75</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>76</b> to a step S<b>77</b>.

The step S<b>77</b> forces the optical head <b>14</b> to suspend the reproduction of the first information signal “A” from the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>.

A step S<b>78</b> subsequent to the step S<b>77</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, first one B<b>1</b> of the second areas <b>13</b><i>b </i>in the optical disc <b>13</b>. After the step S<b>78</b>, the program advances to a step S<b>79</b>.

The step S<b>79</b> decides whether or not the optical head <b>14</b> has reached the target position on the optical disc <b>13</b>. When the optical head <b>14</b> has not reached the target position yet, the step S<b>79</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>79</b> to a step S<b>80</b>.

In this way, the optical head <b>14</b> moves from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b. </i>The seek time Tab related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

The step S<b>80</b> stores the second information signal “B”, which is outputted from the audio-video encoding and decoding unit <b>20</b>, into the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the transfer rate Rb.

A step S<b>81</b> following the step S<b>80</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>81</b> to the step S<b>80</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>81</b> to a step S<b>82</b>.

The step S<b>82</b> transfers the second information signal “B” from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The step S<b>82</b> enables the optical head <b>14</b> to record the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b> at the predetermined constant transfer rate Rp.

A step S<b>83</b> following the step S<b>82</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>83</b> to the step S<b>82</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>83</b> to a step S<b>84</b>.

The step S<b>84</b> forces the optical head <b>14</b> to suspend the recording of the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>.

A step S<b>85</b> subsequent to the step S<b>84</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, second one A<b>2</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>. After the step S<b>85</b>, the program returns to the step S<b>72</b>.

Thus, the optical head <b>14</b> moves from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a</i>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

During the repetitive execution of the program segment in FIG. 12, the target position of the optical head <b>14</b> is sequentially set into correspondence with the first and second areas A<b>1</b>, B<b>1</b>, A<b>2</b>, B<b>2</b>, A<b>3</b>, B<b>3</b>, . . . in the optical disc <b>13</b>. Therefore, the optical head <b>14</b> alternately reproduces the first information signal “A” and records the second information signal “B” while accessing the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b> in the order as “A1, B1, A2, B2, A3, B3, . . . ”.

Preferably, the step S<b>77</b> or the step S<b>84</b> is followed by a step which decides whether or not both the reproduction of the first information signal “A” from the optical disc <b>13</b> and the recording of the second information signal “B” thereon are required to be suspended. In this case, when both the reproduction of the first information signal “A” from the optical disc <b>13</b> and the recording of the second information signal “B” thereon are required to be suspended, the optical head <b>14</b> is controlled to implement the required suspension of reproduction and recording.

It is preferable to provide the optical disc <b>13</b> with a management area separate from the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b. </i>For example, the management area extends in an innermost portion of the optical disc <b>13</b>. After the recording of the second information signal “B” on the second areas <b>13</b><i>b </i>in the optical disc <b>13</b> has been completed, address information of the blocks of the second information signal “B” on the second areas <b>13</b><i>b </i>is recorded on the management area in the optical disc <b>13</b>. Information of the second transfer rate Rb may also be recorded on the management area in the optical disc <b>13</b>.

With reference to FIG. 13, after the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> reaches the related empty value, the first information signal “A” is read out from the memory area <b>19</b><i>a </i>at the transfer rate Ra and the first information signal “A” is transmitted from the first area A<b>1</b> in the optical disc <b>13</b> to the memory area <b>19</b><i>a </i>at the predetermined constant transfer rate Rp. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>a </i>increases at a rate corresponding to “Rp−Ra”.

When the degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related full value, the transmission of the first information signal “A” from the first area A<b>1</b> in the optical disc <b>13</b> to the memory area <b>19</b><i>a </i>is suspended. Then, the optical head <b>14</b> is moved to a position corresponding to the second area B<b>1</b> in the optical disc <b>13</b>. The seek time Tab related to this movement of the optical head <b>14</b> is equal to or shorter than 1.5 seconds. Even after the degree of occupancy of the memory area <b>19</b><i>a </i>reaches the related full value, the first information signal “A” continues to be read out from the memory area <b>19</b><i>a </i>at the transfer rate Ra. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>a </i>decreases at a rate corresponding to “Ra”. The read-out of the first information signal “A” from the memory area <b>19</b><i>a </i>is completed before the optical head <b>14</b> accesses the first area A<b>2</b> in the optical disc <b>13</b>.

The second information signal “B” is stored into the second area <b>19</b><i>b </i>of the track buffer memory <b>19</b> from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. After the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> reaches the related full value, the second information signal “B” is transmitted from the memory area <b>19</b><i>b </i>to the second area B<b>1</b> in the optical disc <b>13</b> at the predetermined constant transfer rate Rp and the second information signal “B” continues to be stored into the memory area <b>19</b><i>b </i>from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>b </i>decreases at a rate corresponding to “Rp−Rb”.

When the degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related empty value, the transmission of the second information signal “B” from the memory area <b>19</b><i>b </i>to the second area B<b>1</b> in the optical disc <b>13</b> is suspended. Then, the optical head <b>14</b> is moved to a position corresponding to the first area A<b>2</b> in the optical disc <b>13</b>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to or shorter than 1.5 seconds. Even after the degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related empty value, the second information signal “B” continues to be stored into the memory area <b>19</b><i>b </i>from the audio-video encoding and decoding unit <b>20</b> at the transfer rate Rb. Thus, during this stage, the degree of occupancy of the memory area <b>19</b><i>b </i>increases at a rate corresponding to “Rb”. The degree of occupancy of the memory area <b>19</b><i>b </i>reaches the related full value before the optical head <b>14</b> accesses the second area B<b>2</b> in the optical disc <b>13</b>.

Preferably, the transfer rate Ra, the transfer rate Rb, the size Ya of each block of the first information signal “A” on one first area <b>13</b><i>a </i>in the optical disc <b>13</b>, the size Yb of each block of the second information signal “B” on one second area <b>13</b><i>b </i>in the optical disc <b>13</b>, the seek time Tab related to the movement of the optical head <b>14</b> from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b </i>of the optical disc <b>13</b>, the seek time Tba related to the movement of the optical head <b>14</b> from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a </i>of the optical disc <b>13</b>, and the minimum capacity Ym of the track buffer memory <b>19</b> are chosen to satisfy the previously-indicated relations (1)-(18).

In the case where a second information signal “B” is required to be recorded during the playback of a first information signal “A”, the second information signal “B” is inputted into the apparatus <b>10</b>A and the transfer rate Rb for the second information signal “B” is set in accordance with user's selection. At this time, the system controller <b>22</b> decides the size Yb of blocks of the second information signal “B” on the basis of the transfer rate Rb, the transfer rate Ra, the seek times, and information of usable areas in the optical disc <b>13</b> according to the previously-indicated relations (9), (10), and (11). If the sizes of all the usable areas in the optical disc <b>13</b> are smaller than the block size Yb of the second information signal “B”, the transfer rate Rb is reduced from the designated value. Preferably, the user is informed of the reduction in the transfer rate Rb. The recording of the second information signal “B” is implemented while the reduced transfer rate Rb is used.

It should be noted that the optical disc <b>13</b> may be replaced by a magnetic disc or a plurality of magnetic discs. In this case, the optical-disc drive portion of the apparatus <b>10</b>A in FIG. 1 is replaced by a magnetic-disc drive portion.

A first example of the magnetic-disc drive portion includes a plurality of magnetic heads for accessing magnetic discs each having a spiral track. The magnetic heads and the magnetic discs are periodically changed and selected to record and reproduce information signals on and from the magnetic discs. Each magnetic disc may have a plurality of concentric tracks.

Second Embodiment

FIG. 14 shows an information-signal recording and reproducing apparatus <b>10</b>B according to a second embodiment of this invention. The apparatus <b>10</b>B in FIG. 14 is similar to the apparatus <b>10</b>A in FIG. 1 except for the following design change.

The apparatus <b>10</b>B in FIG. 14 includes an optical disc drive <b>10</b>D and a solid-state memory unit <b>10</b>M. The solid-state memory unit <b>10</b>M is detachably connected with the optical disc drive <b>10</b>D. Specifically, the solid-state memory unit <b>10</b>M is connected with the optical disc drive <b>10</b>D via a disconnectable connector.

The optical disc drive <b>10</b>D includes a spindle motor <b>11</b>, a turntable <b>12</b>, an optical head (an optical pickup) <b>14</b>, a driver <b>15</b>, an amplifier unit <b>16</b>, and a servo unit <b>17</b>. The solid-state memory unit <b>10</b>M includes a signal processor <b>18</b>, a track buffer memory <b>19</b>, an audio-video encoding and decoding unit <b>20</b>, a memory <b>21</b>, a system controller <b>22</b>, a key input unit <b>23</b>, and an input/output terminal <b>24</b>.

When the solid-state memory unit <b>10</b>M is connected with the optical disc drive <b>10</b>D, the apparatus <b>10</b>B in FIG. 14 operates similarly to the apparatus <b>10</b>A in FIG. <b>1</b>. On the other hand, when the solid-state memory unit <b>10</b>M is disconnected from the optical disc drive <b>10</b>D, at least one of first and second information signals “A” and “B” in the track buffer memory <b>19</b> or the memory <b>21</b> can be played back via the signal processor <b>18</b> and the audio-video encoding and decoding unit <b>20</b>.

Third Embodiment

FIG. 15 shows an information-signal communication apparatus <b>25</b>A according to a third embodiment of this invention. The apparatus <b>25</b>A in FIG. 15 is similar to the apparatus <b>10</b>A in FIG. 1 except for design changes indicated hereinafter.

The apparatus <b>25</b>A in FIG. 15 includes a spindle motor <b>11</b>, a turntable <b>12</b>, an optical head (an optical pickup) <b>14</b>, a driver <b>15</b>, an amplifier unit <b>16</b>, a servo unit <b>17</b>, a signal processor <b>18</b>, a track buffer memory <b>19</b>, and a system controller <b>22</b>. The devices <b>11</b>, <b>12</b>, <b>14</b>, <b>15</b>, <b>16</b>, <b>17</b>, <b>18</b>, <b>19</b>, and <b>22</b> are connected in a manner similar to that in the apparatus <b>10</b>A in FIG. <b>1</b>. The apparatus <b>25</b>A in FIG. 15 further includes an ATAPI (AT attachment packet interface) unit <b>26</b>, that is, an interface <b>26</b> of an ATAPI type. The interface <b>26</b> is connected to the signal processor <b>18</b>.

A host computer or an external apparatus <b>27</b> can be connected with the apparatus <b>25</b>A in FIG. 15 via the interface <b>26</b>. The external apparatus <b>27</b> includes an audio-video encoding and decoding unit <b>20</b>, a memory <b>21</b>, and a host computer unit <b>27</b>A. The memory <b>21</b> and the host computer unit <b>27</b>A are connected to the audio-video encoding and decoding unit <b>20</b>. The audio-video encoding and decoding unit <b>20</b> can be connected with the signal processor <b>18</b> in the apparatus <b>25</b>A via the interface <b>26</b>.

In more detail, the ATAPI unit <b>26</b> includes an interface block. The audio-video encoding and decoding unit <b>20</b> includes an interface block which can be connected with the interface block in the ATAPI unit <b>26</b>. The apparatus <b>27</b> can control the apparatus <b>25</b>A while using control signals in the Mt. Fuji command system.

In the case where first and second information signals “A” and “B” are required to be recorded, the host computer unit <b>27</b>A in the apparatus <b>27</b> transmits information of transfer rates Ra and Rb for the first and second information signals “A” and “B” (transfer-rate representing flags) to the apparatus <b>25</b>A via the audio-video encoding and decoding unit <b>20</b> and the interface <b>26</b>. The audio-video encoding and decoding unit <b>20</b> in the apparatus <b>27</b> transmits the first and second information signals “A” and “B” to the signal processor <b>18</b> in the apparatus <b>25</b>A via the interface <b>26</b>. In addition, the host computer unit <b>27</b>A in the apparatus <b>27</b> transmits a recording start command signal and a recording start address signal to the apparatus <b>25</b>A via the audio-video encoding and decoding unit <b>20</b> and the interface <b>26</b>.

In the case where first and second information signals “A” and “B” are required to be reproduced from an optical disc <b>13</b>, the host computer unit <b>27</b>A in the apparatus <b>27</b> transmits a playback start command signal and a disc address signal to the apparatus <b>25</b>A via the audio-video encoding and decoding unit <b>20</b> and the interface <b>26</b>. The apparatus <b>25</b>A reproduces a signal (for example, control data or management information) from a portion of the optical disc <b>13</b> whose position is designated by the disc address signal. The host computer unit <b>27</b>A in the apparatus <b>27</b> receives the reproduced signal from the apparatus <b>25</b>A via the interface <b>26</b> and the audio-video encoding and decoding unit <b>20</b>, and calculates transfer rates Ra and Rb on the basis of the reproduced signal. The host computer unit <b>27</b>A in the apparatus <b>27</b> transmits information of the calculated transfer rates Ra and Rb (transfer-rate representing flags) to the apparatus <b>25</b>A via the audio-video encoding and decoding unit <b>20</b> and the interface <b>26</b>. Then, the apparatus <b>25</b>A reproduces the first and second information signals “A” and “B” while using the transfer rates Ra and Rb.

The interface <b>26</b> may be of an IEEE1394 type rather than the ATAPI type. The interface <b>26</b> may be of a wireless type using a radio signal or a light signal.

Fourth Embodiment

FIG. 16 shows an information-signal communication apparatus <b>25</b>B according to a fourth embodiment of this invention. The apparatus <b>25</b>B in FIG. 16 is similar to the apparatus <b>25</b>A in FIG. 15 except for the following design change.

The apparatus <b>25</b>B in FIG. 16 includes an optical disc drive <b>25</b>D and a solid-state memory unit <b>25</b>M. The solid-state memory unit <b>25</b>M is detachably connected with the optical disc drive <b>25</b>D and an interface <b>26</b>. Specifically, the solid-state memory unit <b>25</b>M is connected with the optical disc drive <b>25</b>D and the interface <b>26</b> via disconnectable connectors.

The optical disc drive <b>25</b>D includes a spindle motor <b>11</b>, a turntable <b>12</b>, an optical head (an optical pickup) <b>14</b>, a driver <b>15</b>, an amplifier unit <b>16</b>, and a servo unit <b>17</b>. The solid-state memory unit <b>25</b>M includes a signal processor <b>18</b>, a track buffer memory <b>19</b>, and a system controller <b>22</b>. The signal processor <b>18</b> can be connected with the interface <b>26</b>.

A host computer or an external apparatus <b>27</b> can be connected with the signal processor <b>18</b> in the solid-state memory unit <b>25</b>M via the interface <b>26</b>. The external apparatus <b>27</b> includes an audio-video encoding and decoding unit <b>20</b>, a memory <b>21</b>, and a host computer unit <b>27</b>A. The memory <b>21</b> and the host computer unit <b>27</b>A are connected to the audio-video encoding and decoding unit <b>20</b>. The audio-video encoding and decoding unit <b>20</b> can be connected with the signal processor <b>18</b> in the apparatus <b>25</b>A via the interface <b>26</b>.

When the solid-state memory unit <b>25</b>M is connected with the optical disc drive <b>25</b>D and the interface <b>26</b>, the apparatus <b>25</b>B in FIG. 16 operates similarly to the apparatus <b>25</b>A in FIG. <b>15</b>. On the other hand, when the solid-state memory unit <b>25</b>M is disconnected from the optical disc drive <b>25</b>D and the interface <b>26</b>, at least one of first and second information signals “A” and “B” in the track buffer memory <b>19</b> can be played back via the signal processor <b>18</b>.

Fifth Embodiment

FIG. 17 shows an information-signal recording and reproducing apparatus <b>110</b> according to a fifth embodiment of this invention. The apparatus <b>110</b> operates on an information-signal recording medium including an optical disc. Examples of the optical disc are a DVD-ROM, a DVD-RAM, a DVD-RW, and a DVD+RW. Alternatively, the information recording medium may include a magnetic disc such as a hard disc or a floppy disc. The information recording medium may include a semiconductor memory.

As shown in FIG. 17, the apparatus <b>110</b> includes a spindle motor <b>111</b>, and a turntable <b>112</b> connected to the shaft of the spindle motor <b>111</b>. An optical disc (an information-signal recording medium) <b>113</b> can be placed on the turntable <b>112</b>. The apparatus <b>110</b> further includes an optical head (an optical pickup) <b>114</b>, a driver <b>115</b>, an amplifier unit <b>116</b>, a servo unit <b>117</b>, a signal processor <b>118</b>, a track buffer memory <b>119</b>, an audio-video encoding and decoding unit <b>120</b>, a memory <b>121</b>, a system controller <b>122</b>, a key input unit <b>123</b>, an NTSC encoder <b>124</b>, a display <b>125</b>, and input terminals <b>126</b>(1), <b>126</b>(2), . . . , and <b>126</b>(n). Here, “n” denotes a predetermined natural number equal to or greater than 2. In addition, the apparatus <b>110</b> includes a satellite digital broadcasting reception antenna <b>141</b>, a satellite digital broadcasting decoder <b>142</b>, a switch <b>143</b>, a stream converter <b>144</b>, and a terminal <b>145</b>.

When the optical disc <b>113</b> is placed on the turntable <b>112</b>, the spindle motor <b>111</b> rotates the turntable <b>112</b> and the optical disc <b>113</b>. In the case where the optical disc <b>113</b> is of a rewritable type, the optical head <b>114</b> writes and reads information thereon and therefrom. In the case where the optical disc <b>113</b> is designed exclusively for playback, the optical head <b>114</b> only reads information therefrom. The spindle motor <b>111</b> is connected to the driver <b>115</b> and the servo unit <b>117</b>. The optical head <b>114</b> is connected to the amplifier unit <b>116</b> and the driver <b>115</b>. The amplifier unit <b>116</b> is connected to the servo unit <b>117</b> and the signal processor <b>118</b>. The driver <b>115</b> is connected to the servo unit <b>117</b>. The signal processor <b>118</b> is connected to the track buffer memory <b>119</b> and the audio-video encoding and decoding unit <b>120</b>. The audio-video encoding and decoding unit <b>120</b> is connected to the memory <b>121</b> and the input terminals <b>126</b>(1)-<b>126</b>(n). The system controller <b>122</b> is connected to the amplifier unit <b>116</b>, the servo unit <b>117</b>, the signal processor <b>118</b>, the audio-video encoding and decoding unit <b>120</b>, and the key input unit <b>123</b>.

The NTSC encoder <b>124</b> is connected to the audio-video encoding and decoding unit <b>120</b>. The display <b>125</b> is connected to the NTSC encoder <b>124</b>. The satellite digital broadcasting reception antenna <b>141</b> is connected to the satellite digital broadcasting decoder <b>142</b>. The satellite digital broadcasting decoder <b>142</b> is connected to the switch <b>143</b>. The switch <b>143</b> is connected to the stream converter <b>144</b>. The switch <b>143</b> is connected to the Internet via the terminal <b>145</b>. The stream converter <b>144</b> is connected to the signal processor <b>118</b>. The satellite digital broadcasting decoder <b>142</b>, the switch <b>143</b>, the stream converter <b>144</b>, and the system controller <b>122</b> are connected to each other.

The spindle motor <b>111</b> is driven and controlled by the driver <b>115</b>. The spindle motor <b>111</b> rotates the turntable <b>112</b> and the optical disc <b>113</b>. The spindle motor <b>111</b> is provided with an FG generator and a rotational position sensor (an angular position sensor). The rotational position sensor includes, for example, a Hall element. The FG generator outputs an FG signal (a rotational speed signal). The Hall element outputs a rotational position signal. The FG signal and the rotational position signal are fed back to the driver <b>115</b> and the servo unit <b>117</b> as rotation servo signals.

The optical head <b>114</b> faces the optical disc <b>113</b> placed on the turntable <b>112</b>. A feed motor (not shown) moves the optical head <b>114</b> radially with respect to the optical disc <b>113</b>. The feed motor is driven by the driver <b>115</b>. The optical head <b>114</b> includes a semiconductor laser, a collimator lens, and an objective lens. The semiconductor laser acts as a source for emitting a light beam (a laser beam). The emitted laser beam is focused into a laser spot on the optical disc <b>113</b> by the collimator lens and the objective lens. The optical head <b>114</b> includes a 2-axis actuator for driving the objective lens to implement focusing and tracking of the laser spot with respect to the optical disc <b>113</b>. The semiconductor laser is driven by a laser drive circuit in the optical head <b>114</b>. In the case where an information signal such as an audio signal or an audio-video signal is recorded, the information signal is subjected to waveform correction by a waveform correction circuit in the amplifier unit <b>116</b> before being fed to the laser drive circuit. The 2-axis actuator is driven by the driver <b>115</b>.

The key input unit <b>123</b> includes a plurality of keys which can be operated by a user. The key input unit <b>123</b> generates command signals in accordance with its operation by the user. The command signals are transmitted from the key input unit <b>123</b> to the system controller <b>122</b>. The command signals include a command signal for starting a recording mode of operation of the apparatus <b>110</b>, and a command signal for starting a playback mode of operation of the apparatus <b>110</b>. The key input unit <b>123</b> generates control data in accordance with its operation by the user. The control data are transmitted from the key input unit <b>123</b> to the system controller <b>122</b>.

The system controller <b>122</b> includes, for example, a microcomputer or a similar device which operates in accordance with a program stored in its internal ROM. The system controller <b>122</b> controls the amplifier unit <b>116</b>, the servo unit <b>117</b>, the signal processor <b>118</b>, and the audio-video encoding and decoding unit <b>120</b> in response to the command signals fed from the key input unit <b>123</b>.

Control data can be fed to the system controller <b>122</b> via an input terminal (not shown). The control data fed to the system controller <b>122</b> via the input terminal, and the control data fed to the system controller <b>122</b> from the key input unit <b>123</b> include a signal for adjusting the resolution of pictures represented by contents information to be recorded, a signal for separating quickly-moving scenes such as car racing scenes represented by contents information, and a signal for giving priority to a recording time. The system controller <b>122</b> changes an actual recording time in accordance with the control data. The system controller <b>122</b> enables the setting of the actual recording time to be selected by the user.

When the apparatus <b>110</b> is required to start to operate in the playback mode, the key input unit <b>123</b> is actuated to generate the playback start command signal. The playback start command signal is transmitted from the key input unit <b>123</b> to the system controller <b>122</b>. The system controller <b>122</b> controls the amplifier unit <b>116</b> and the servo unit <b>117</b> in response to the playback start command signal, thereby starting the playback mode of operation of the apparatus <b>110</b>. The control of the servo unit <b>117</b> includes steps of controlling the driver <b>115</b>. Firstly, the system controller <b>122</b> starts rotation of the optical disc <b>113</b> and application of a laser spot thereon through the control of the driver <b>115</b>. The optical head <b>114</b> is controlled by the driver <b>115</b>, thereby reading out address information from the optical disc <b>113</b>. For example, the address information is contained in management information stored in a management area of the optical disc <b>113</b>. The read-out address information is transmitted from the optical head <b>114</b> to the system controller <b>122</b> via the amplifier unit <b>116</b>. The system controller <b>122</b> finds or decides a target sector (a target track portion) to be played back by referring to the address information. The system controller <b>122</b> controls the optical head <b>114</b> via the servo unit <b>117</b>, the driver <b>115</b>, and the feed motor, thereby moving the optical head <b>114</b> radially with respect to the optical disc <b>113</b> and hence moving the laser spot to the target sector on the optical disc <b>113</b>. When the movement of the laser spot to the target sector is completed, the system controller <b>122</b> operates to start the reproduction of a signal from the target sector on the optical disc <b>113</b>. In this way, the playback mode of operation of the apparatus <b>110</b> is started. During the playback mode of operation of the apparatus <b>110</b>, the target sector is repetitively changed from one to another.

During the playback mode of operation of the apparatus <b>110</b>, the optical head <b>114</b> scans the optical disc <b>113</b> and generates an RF signal containing information read out therefrom. A unit of generation of the RF signal corresponds to one correction block of the information recorded on the optical disc <b>113</b>. The optical head <b>114</b> outputs the RF signal to the amplifier unit <b>116</b>. The amplifier unit <b>116</b> enlarges the RF signal. In addition, the amplifier unit <b>116</b> generates a main reproduced signal, and tracking and focusing servo signals (tracking error and focusing error signals) from the enlarged RF signal. The amplifier unit <b>116</b> includes an equalizer for optimizing the frequency aspect of the main reproduced signal. Also, the amplifier unit <b>116</b> includes a PLL (phase locked loop) circuit for extracting a bit clock signal from the equalized main reproduced signal, and for generating a speed servo signal from the equalized main reproduced signal. Furthermore, the amplifier unit <b>116</b> includes a jitter generator for comparing the time bases of the bit clock signal and the equalized main reproduced signal, and for detecting jitter components from the results of the time-base comparison. A signal of the detected jitter components is transmitted from the amplifier unit <b>116</b> to the system controller <b>122</b>. The tracking and focusing servo signals and the speed servo signal are transmitted from the amplifier unit <b>116</b> to the servo unit <b>117</b>. The equalized main reproduced signal is transmitted from the amplifier unit <b>116</b> to the signal processor <b>118</b>.

The servo unit <b>117</b> receives the speed servo signal and the tracking and focusing servo signals from the amplifier unit <b>116</b>. The servo unit <b>117</b> receives the rotation servo signals from the spindle motor <b>111</b>. In response to these servo signals, the servo unit <b>117</b> implements corresponding servo control processes.

Specifically, the servo unit <b>117</b> generates a rotation control signal on the basis of the speed servo signal and the rotation servo signals. The rotation control signal is transmitted from the servo unit <b>117</b> to the spindle motor <b>111</b> via the driver <b>115</b>. The spindle motor <b>111</b> rotates at a speed depending on the rotation control signal. The rotation control signal is designed to rotate the optical disc <b>113</b> at a given constant linear velocity.

In addition, the servo unit <b>117</b> generates servo control signals on the basis of the focusing and tracking servo signals. The servo control signals are transmitted from the servo unit <b>117</b> to the 2-axis actuator in the optical head <b>114</b> via the driver <b>115</b>. The 2-axis actuator controls the laser spot on the optical disc <b>113</b> in response to the servo control signals, and thereby implements focusing and tracking of the laser spot with respect to the optical disc <b>113</b>.

During the playback mode of operation of the apparatus <b>110</b>, the signal processor <b>118</b> receives the main reproduced signal from the amplifier unit <b>116</b>. The signal processor <b>118</b> is controlled by the system controller <b>122</b>, thereby converting the main reproduced signal into a corresponding reproduced digital signal. The signal processor <b>118</b> detects a sync signal from the reproduced digital signal. The signal processor <b>118</b> decodes an EFM+ signal (an 8-16 modulation signal) of the reproduced digital signal into NRZ data, that is, non-return-to-zero data. The signal processor <b>118</b> subjects the NRZ data to an error correction process for every correction block, thereby generating a sector address signal and a plurality of information signals (“n” information signals). Here, “n” denotes a predetermined natural number equal to or greater than 2. The “n” information signals include a first information signal, a second information signal, . . . , and an n-th information signal. The sector address signal represents the address of a currently-accessed sector on the optical disc <b>113</b>. The sync signal and the sector address signal are fed from the signal processor <b>118</b> to the system controller <b>122</b>. It should be noted that the “n” information signals generated by the signal processor <b>118</b> correspond to information signals resulting from compression at variable transfer rates (variable transmission rates) during a recording mode of operation.

During the playback mode of operation of the apparatus <b>110</b>, the signal processor <b>118</b> temporarily stores the “n” information signals in the track buffer memory <b>119</b>. Thus, the signal processor <b>118</b> writes the “n” information signals into the track buffer memory <b>119</b>, and reads the “n” information signals therefrom. Writing and reading the “n” information signals into and from the track buffer memory <b>119</b> are controlled to absorb a time-domain change in the transfer rates of the “n” information signals. The track buffer memory <b>119</b> includes, for example, a D-RAM having a capacity of 64 Mbytes. The signal processor <b>118</b> outputs the read-out signal (the “n” information signals read out from the track buffer memory <b>119</b>) to the audio-video encoding and decoding unit <b>120</b>.

In the case where the “n” information signals fed from the track buffer memory <b>119</b> via the signal processor <b>118</b> are compressed MPEG2 data in which audio data and video data are multiplexed, the audio-video encoding and decoding unit <b>120</b> separates the “n” information signals into compressed audio data and compressed video data. The audio-video encoding and decoding unit <b>120</b> expands and decodes the compressed audio data into non-compressed audio data. In addition, the audio-vide encoding and decoding unit <b>120</b> expands and decodes the compressed video data into non-compressed video data. During the expansively decoding process, the audio-video encoding and decoding unit <b>120</b> temporarily stores signals and data in the memory <b>121</b>. The memory <b>121</b> includes, for example, a D-RAM having a capacity of 64 Mbytes. The audio-video encoding and decoding unit <b>120</b> converts the non-compressed audio data into a corresponding analog audio signal through digital-to-analog conversion. Also, the audio-video encoding and decoding unit <b>120</b> converts the non-compressed video data into a corresponding analog video signal through digital-to-analog conversion. It should be noted that the conversion of the non-compressed audio and video data into the analog audio and video signals may be implemented by digital-to-analog converters provided externally of the audio-video encoding and decoding unit <b>120</b>. The audio-video encoding and decoding unit <b>120</b> outputs the analog audio signal and the analog video signal to the NTSC converter <b>124</b>. The analog audio signal passes through the NTSC converter <b>124</b> before being applied to loudspeakers provided in the body of the display <b>125</b>. The NTSC converter <b>124</b> changes the analog video signal into a corresponding NTSC video signal. The NTSC converter <b>124</b> outputs the NTSC video signal to the display <b>125</b>.

The data rate of the expansively decoding process by the audio-video encoding and decoding unit <b>120</b>, that is, the data transfer rate (the data transmission rate) in the expansively decoding process, is equalized to an expansion data rate which is set in accordance with the type of the related recording mode of operation of the apparatus <b>110</b>. Specifically, the audio-video encoding and decoding unit <b>120</b> can implement the expansively decoding process at a expansion data rate which can be changed among plural different expansion data rates. The audio-video encoding and decoding unit <b>120</b> selects one from among the plural different expansion data rates as a desired expansion data rate in accordance with the type of the related recording mode of operation of the apparatus <b>110</b>. The audio-video encoding and decoding unit <b>120</b> executes the expansively encoding process at the desired expansion data rate. Information of the type of the recording mode of operation of the apparatus <b>110</b> is recorded on the optical disc <b>113</b> as control data which may be contained in the management information. During the playback of the optical disc <b>113</b>, the control data are read out therefrom before being transmitted to the system controller <b>122</b>. The system controller <b>122</b> sets the expansion data rate in the audio-video encoding and decoding unit <b>120</b> in accordance with the control data.

When the apparatus <b>110</b> is required to start to operate in the recording mode, the key input unit <b>123</b> is actuated to generate the recording start command signal. The recording start-command signal is transmitted from the key input unit <b>123</b> to the system controller <b>122</b>. The system controller <b>122</b> controls the amplifier unit <b>116</b> and the servo unit <b>117</b> in response to the recording start command signal, thereby starting the recording mode of operation of the apparatus <b>110</b>. The control of the servo unit <b>117</b> includes steps of controlling the driver <b>115</b>. Firstly, the system controller <b>122</b> starts rotation of the optical disc <b>113</b> and application of a laser spot thereon through the control of the driver <b>115</b>. The optical head <b>114</b> is controlled by the driver <b>115</b>, thereby reading out address information from the optical disc <b>113</b>. For example, the address information is contained in management information stored in the management area of the optical disc <b>113</b>. The read-out address information is transmitted from the optical head <b>114</b> to the system controller <b>122</b> via the amplifier unit <b>116</b>. The system controller <b>122</b> finds or decides a target sector (a target track portion), on which a signal is to be recorded, by referring to the address information. The system controller <b>122</b> controls the optical head <b>114</b> via the servo unit <b>117</b>, the driver <b>115</b>, and the feed motor, thereby moving the optical head <b>114</b> radially with respect to the optical disc <b>113</b> and hence moving the laser spot to the target sector on the optical disc <b>113</b>. During the recording mode of operation of the apparatus <b>110</b>, the target sector is repetitively changed from one to another.

During the recording mode of operation of the apparatus <b>110</b>, “n” analog information signals to be recorded are fed to the audio-video encoding and decoding unit <b>120</b> via the input terminals <b>126</b>(1)-<b>126</b>(n) respectively. The audio-video encoding and decoding unit <b>120</b> converts the “n” analog information signals into corresponding “n” digital information signals through analog-to-digital conversion. It should be noted that the conversion of the “n” analog information signals into the “n” digital information signals may be implemented by analog-to-digital converters provided externally of the audio-video encoding and decoding unit <b>120</b>. The audio-video encoding and decoding unit <b>120</b> compressively encodes the “n” digital information signals into “n” MPEG2 information signals at rates depending on the type of the recording mode. The audio-video encoding and decoding unit <b>120</b> outputs the “n” MPEG2 information signals to the signal processor <b>118</b> on a time sharing basis. The data rates of the compressively encoding process by the audio-video encoding and decoding unit <b>120</b>, that is, the data transfer rates (the data transmission rates) in the compressively encoding process, are equalized to compression data rates which are selected from among plural different rates in accordance with the type of the recording mode of operation of the apparatus <b>110</b>. During the compressively encoding process, the audio-video encoding and decoding unit <b>120</b> temporarily stores data in the memory <b>121</b>.

It should be noted that the “n” MPEG2 information signals may be replaced by still-picture data or computer data such as program file data. In this case, the still-picture data or the computer data are transmitted to the system controller <b>122</b> via an interface (not shown). The system controller <b>122</b> transfers the still-picture data or the computer data to the signal processor <b>118</b>.

Alternatively, the “n” MPEG2 information signals may be replaced by “n” compression-resultant information signals composing a transport stream signal. In this case, radio signals containing “n” compression-resultant information signals are received by the satellite digital broadcasting reception antenna <b>141</b>, and the received radio signals are fed from the antenna <b>141</b> to the satellite digital broadcasting decoder <b>142</b>. The satellite digital broadcasting decoder <b>142</b> subjects the received radio signals to QPSK demodulation, an error correction process, and a stream generating process, thereby converting the received radio signals into a transport stream signal composed of 188-byte segments representative of the “n” compression-resultant information signals. The satellite digital broadcasting decoder <b>142</b> outputs the transport stream signal to the switch <b>143</b>. In addition, “n” compression-resultant information signals composing a transport stream signal are fed from the Internet to the switch <b>143</b> via the terminal <b>145</b>. The switch <b>143</b> selects one of a set of the “n” compression-resultant information signals (the transport stream signal) fed from the satellite digital broadcasting decoder <b>142</b> and a set of the “n” compression-resultant information signals (the transport stream signal) fed via the terminal <b>145</b>, and outputs the selected signal set to the stream converter <b>144</b>. The selection by the switch <b>143</b> responds to a switch control signal fed from the system controller <b>122</b>. The switch control signal is generated in response to, for example, user's operation of the key input unit <b>123</b>. The stream converter <b>144</b> changes the output signals of the switch <b>143</b> into a program stream composed of 2048-byte segments representative of the “n” selected compression-resultant information signals. The stream converter <b>144</b> may encrypt the “n” selected compression-resultant information signals in accordance with key information recorded on the optical disc <b>113</b>. The stream converter <b>144</b> outputs the program stream to the signal processor <b>118</b>.

During the recording mode of operation of the apparatus <b>110</b>, the signal processor <b>118</b> adds error correction code signals (ECC signals) to the “n” MPEG2 information signals, the still-picture data, the computer data, or the “n” compression-resultant information signals. The signal processor <b>118</b> subjects the ECC-added data (the ECC-added signals) to NRZ and EFM+ encoding processes. The signal processor <b>118</b> adds a sync signal to the encoding-resultant data to form sync-added data. The sync signal is fed from the system controller <b>122</b>. The sync-added data are temporarily stored in the track buffer memory <b>119</b>. The sync-added data are read out from the track buffer memory <b>119</b> at a data rate corresponding to a data rate of signal recording on the optical disc <b>113</b>. The signal processor <b>118</b> subjects the read-out data to given modulation for record. The signal processor <b>118</b> outputs the modulation-resultant signal to the amplifier unit <b>116</b>. The amplifier unit <b>116</b> corrects the waveform of the output signal of the signal processor <b>118</b>. The amplifier unit <b>116</b> outputs the waveform-correction-resultant signal to the laser drive circuit in the optical head <b>114</b>. The optical head <b>114</b> records the output signal of the amplifier unit <b>116</b> on the target sector (the target track portion) on the optical disc <b>113</b>.

The amplifier unit <b>116</b> informs the system controller <b>122</b> of detected jitter components. The system controller <b>122</b> subjects the detected jitter components to analog-to-digital conversion to generate a measured jitter value. During the recording mode of operation of the apparatus <b>110</b>, the system controller <b>122</b> adjusts the degree or characteristic of the waveform correction by the amplifier unit <b>116</b> in response to the measured jitter value and an asymmetry value.

Operation of the apparatus <b>110</b> can be changed among various modes. During a first mode of operation, the apparatus <b>110</b> reproduces an audio signal or an audio-video signal from the optical disc <b>113</b>. During a second mode of operation, the apparatus <b>110</b> records an audio signal or an audio-video signal on the optical disc <b>113</b>. During a third mode of operation, the apparatus <b>110</b> records an audio signal or an audio-video signal on one area of the optical disc <b>113</b> while reproducing an audio signal or an audio-video signal from another area of the optical disc <b>113</b>. During a fourth mode of operation, the apparatus <b>110</b> reproduces an audio signal or an audio-video signal from one area of the optical disc <b>113</b> while recording an audio signal or an audio-video signal on another area of the optical disc <b>113</b>. During a fifth mode of operation, the apparatus <b>110</b> reproduces an audio signal or an audio-video signal from one area of the optical disc <b>113</b> while reproducing an audio signal or an audio-video signal from another area of the optical disc <b>113</b>. During a sixth mode of operation, the apparatus <b>110</b> records an audio signal or an audio-video signal on one area of the optical disc <b>113</b> while recording an audio signal or an audio-video signal on another area of the optical disc <b>113</b>. These various modes of operation of the apparatus <b>110</b> meet user's requests for the implementation of an after-recording process and a different-channel-program recording process.

The apparatus <b>110</b> can record “n” information signals on different areas of the optical disc <b>113</b>, respectively, on a time sharing basis. The “n” information signals are “n” audio-video information signals respectively. Alternatively, the “n” information signals may be “n” audio information signals respectively. The apparatus <b>110</b> can record only one of the “n” information signals on the optical disc <b>113</b>.

The apparatus <b>110</b> can reproduce “n” information signals from different areas of the optical disc <b>113</b>, respectively, on a time sharing basis. The “n” information signals are “n” audio-video information signals respectively. Alternatively, the “n” information signals may be “n” audio information signals respectively. The apparatus <b>110</b> can reproduce only one of the “n” information signals from the optical disc <b>113</b>.

FIG. 18 shows a portion of the apparatus <b>110</b>. The amplifier unit <b>116</b> and the signal processor <b>118</b> are omitted from FIG. 18 for a better understanding. As shown in FIG. 18, the optical disc <b>113</b> has first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) assigned to first, second, . . . , and n-th information signals respectively. The first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) are separate from each other. Each of the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) is divided into separate equal-size sub-areas. The first information signal is divided into blocks each having a predetermined size (a predetermined total number of bits) Y<b>1</b>. The sub-areas of the first area <b>113</b>(1) are allocated to the blocks of the first information signal, respectively. The second information signal is divided into blocks each having a predetermined size (a predetermined total number of bits) Y<b>2</b>. The sub-areas of the second area <b>113</b>(2) are allocated to the blocks of the second information signal, respectively. The third and later information signals, and the third and later areas <b>113</b>(3)−are similarly designed. The n-th information signal is divided into blocks each having a predetermined size (a predetermined total number of bits) Yn. The sub-areas of the n-th area <b>113</b>(n) are allocated to the blocks of the n-th information signal, respectively. Each of the predetermined sizes Y<b>1</b>, Y<b>2</b>, . . . , and Yn is a unit (a unit capacity) for continuous reproduction (or continuous recording) of information, or a unit (a unit capacity) for reproduction (or recording) of continuous information. The first, second, . . . , and n-th information signals are related or unrelated to each other. Each of the first, second, . . . , and n-th information signals represents audio data, video data, audio-video data, or computer data.

As shown in FIG. 19, the sub-areas in the first area <b>113</b>(1) of the optical disc <b>113</b> are given addresses A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively. Thus, the sub-areas in the first area <b>113</b>(1) are also referred to as the sub-areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The blocks of the first information signal are assigned to the sub-areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . , respectively. Preferably, the size Y<b>1</b> of the blocks of the first information signal is equal to the size of the sub-areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . . The placement of the sub-areas in the first area <b>113</b>(1) is designed to meet requirements for a seek time. As shown in FIG. 20, the sub-areas in the second area <b>113</b>(2) of the optical disc <b>113</b> are given addresses B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively. Thus, the sub-areas in the second area <b>113</b>(2) are also referred to as the sub-areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The blocks of the second information signal are assigned to the sub-areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . , respectively. Preferably, the size Y<b>2</b> of the blocks of the second information signal is equal to the size of the sub-areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . . The placement of the sub-areas in the second area <b>113</b>(2) is designed to meet requirements for a seek time. The sub-areas in each of the third and later areas <b>113</b>(3) . . . of the optical disc <b>113</b>, and the blocks of each of the third and later information signals are similarly designed. As shown in FIG. 21, the sub-areas in the n-th area <b>113</b>(n) of the optical disc <b>113</b> are given addresses N<b>1</b>, N<b>2</b>, N<b>3</b>, . . . , respectively. Thus, the sub-areas in the n-th area <b>113</b>(n) are also referred to as the sub-areas N<b>1</b>, N<b>2</b>, N<b>3</b>, . . . . The blocks of the n-th information signal are assigned to the sub-areas N<b>1</b>, N<b>2</b>, N<b>3</b>, . . . , respectively. Preferably, the size Yn of the blocks of the n-th information signal is equal to the size of the sub-areas N<b>1</b>, N<b>2</b>, N<b>3</b>, . . . . The placement of the sub-areas in the n-th area <b>113</b>(n) is designed to meet requirements for a seek time.

During an example of the recording or playback mode of operation of the apparatus <b>110</b>, the optical head <b>114</b> accesses the sub-area A<b>1</b> in the first area <b>113</b>(1) of the optical disc <b>113</b> before accessing the sub-area B<b>1</b> in the second area <b>113</b>(2) of the optical disc <b>113</b>. The sub-area A<b>1</b> and the sub-area B<b>1</b> are located relative to each other so that the optical head <b>114</b> can move therebetween in a predetermined time (equal to, for example, 1.5 seconds). Therefore, the maximum seek time during which the optical head <b>114</b> moves between the sub-area A<b>1</b> and the sub-area B<b>1</b> is equal to the predetermined time (for example, 1.5 seconds). Similarly, the maximum seek time during which the optical head <b>114</b> moves from one sub-area to a next sub-area is equal to the predetermined time (for example, 1.5 seconds).

As shown in FIG. 18, an innermost portion of the optical disc <b>113</b> has a management area <b>113</b><i>x. </i>As shown in FIG. 22, the management area <b>113</b><i>x </i>is divided into separate sub-areas which are given addresses X<b>1</b>, X<b>2</b>, X<b>3</b>, . . . , respectively. Thus, the sub-areas in the management area <b>113</b><i>x </i>are also referred to as the sub-areas X<b>1</b>, X<b>2</b>, X<b>3</b>, . . . . In the case where the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) of the optical disc <b>113</b> store the first, second, and n-th information signals respectively, the management area <b>113</b><i>x </i>is loaded with copyright information, title information, signals representative of the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn, and signals representative of start addresses and end addresses for the first, second, and n-th information signals. In the case where the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) of the optical disc <b>113</b> are unoccupied and do not store the first, second, and n-th information signals respectively, the management area <b>113</b><i>x </i>is loaded with signals representative of the start addresses and the end addresses of the unoccupied regions (the unoccupied areas).

The track buffer memory <b>119</b> has first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) which are assigned to the first, second, . . . , and n-th information signals respectively.

With reference to FIG. 18, the optical head <b>114</b> transfers the first, second, . . . , and n-th information signals between the optical disc <b>113</b> and the track buffer memory <b>119</b> on a time sharing basis and at a predetermined constant transfer rate Rp. The predetermined constant transfer rate Rp is equal to, for example, 25 Mbps.

The first information signal is transferred between the track buffer memory <b>119</b> and the audio-video encoding and decoding unit <b>120</b> at a transfer rate R<b>1</b> selected from among predetermined values. All the predetermined values are lower than the predetermined constant transfer rate Rp related to the optical head <b>114</b>. The second information signal is transferred between the track buffer memory <b>119</b> and the audio-video encoding and decoding unit <b>120</b> at a transfer rate R<b>2</b> changeable among the predetermined values. Similarly, the third and later information signals are transferred between the track buffer memory <b>119</b> and the audio-video encoding and decoding unit <b>120</b>. The n-th information signal is transferred between the track buffer memory <b>119</b> and the audio-video encoding and decoding unit <b>120</b> at a transfer rate Rn changeable among the predetermined values.

As will be mentioned later, the apparatus <b>110</b> can substantially continuously and simultaneously record or reproduce the contents of at least two of the “n” information signals.

In more detail, each of the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn is selected from among a value of 8 Mbps which corresponds to a recording time of 2 hours and a high picture quality, a value of 4 Mbps which corresponds to a recording time of 4 hours and a slightly high picture quality, and a value of 2 Mpbs which corresponds to a recording time of 8 hours and a normal picture quality. Ones of these values can be designated as desired values of the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn according to user's operation of the key input unit <b>123</b> (see FIG. <b>17</b>). A value of 17 Mbps may be added to the candidate values. During the recording of the “n” information signals on the optical disc <b>113</b>, the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are set to the desired values designated by user's operation of the key input unit <b>123</b>. During the reproduction of the “n” information signals from the optical disc <b>113</b>, information of recording compression rates is derived from control data in the “n” information signals, and the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are set in response to the recording compression rates. Alternatively, during the reproduction of the “n” information signals from the optical disc <b>113</b>, control data (management information) representative of transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are reproduced from the optical disc <b>113</b>, and the actual transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are set in accordance with the reproduced control data.

The system controller <b>122</b> (see FIG. 17) controls the track buffer memory <b>119</b> via the signal processor <b>118</b> (see FIG. <b>17</b>). The system controller <b>122</b> virtually divides or partitions the track buffer memory <b>119</b> into the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n). Specifically, the system controller <b>122</b> sets the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) in the track buffer memory <b>119</b> in response to the values of the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn. The ratio in capacity among the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) depends on the ratio among the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn. Regarding the first area <b>119</b>(1) in the track buffer memory <b>119</b>, the system controller <b>122</b> sets an empty value and a full value in response to the value of the transfer rate R<b>1</b>. The empty value corresponds to a slightly occupied state or a substantially empty state of the first area <b>119</b>(1). The full value corresponds to a fully occupied state of the first area <b>119</b>(1). Regarding the second area <b>119</b>(2) in the track buffer memory <b>119</b>, the system controller <b>122</b> sets an empty value and a full value in response to the value of the transfer rate R<b>2</b>. The empty value corresponds to a slightly occupied state or a substantially empty state of the second area <b>119</b>(2). The full value corresponds to a fully occupied state of the second area <b>119</b>(2). Similarly, regarding each of the third and later areas <b>119</b>(3) . . . in the track buffer memory <b>119</b>, the system controller <b>122</b> sets an empty value and a full value in response to the value of the related transfer rate. Regarding the n-th area <b>119</b>(n) in the track buffer memory <b>119</b>, the system controller <b>122</b> sets an empty value and a full value in response to the value of the transfer rate Rn. The empty value corresponds to a slightly occupied state or a substantially empty state of the n-th area <b>119</b>(n). The full value corresponds to a fully occupied state of the n-th area <b>119</b>(n). The system controller <b>122</b> always monitors the degree of occupancy of each of the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) which varies between the related empty value and the related full value under normal conditions.

Alternatively, the division of the track buffer memory <b>119</b> into the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) may be responsive to the type of the mode of operation of the apparatus <b>110</b>. For example, in the case of the operation mode during which the apparatus <b>110</b> reproduces first one of the “n” information signals and records second one of the “n” information signals, greater one of the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) is assigned to the information signal to be recorded while smaller one is assigned to the reproduced information signal. This design reliably prevents the occurrence of an interruption of the continuously recording of the contents of the information signal. The system controller <b>122</b> implements the division of the track buffer memory <b>119</b> into the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) when receiving a recording start command signal or a playback start command signal. Preferably, the system controller <b>122</b> implements the division of the track buffer memory <b>119</b> after confirming the absence of data from the track buffer memory <b>119</b> which are being reproduced or recorded.

A first mode of operation of the apparatus <b>110</b> is executed in the case where the optical disc <b>113</b> is designed exclusively for playback. During the first mode of operation, the optical head <b>114</b> reproduces the first, second, . . . , and n-th information signals from the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) of the optical disc <b>113</b> on a time sharing basis. The first, second, . . . , and n-th information signals are transmitted from the optical head <b>114</b> to the track buffer memory <b>119</b>. The first, second, . . . , and n-th information signals are stored into the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) of the track buffer memory <b>119</b> at the predetermined constant transfer rate Rp. The first, second, . . . , and n-th information signals are transmitted from the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) of the track buffer memory <b>119</b> at the respective transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn lower than the predetermined constant transfer rate Rp.

A second mode of operation of the apparatus <b>110</b> is executed in the case where the optical disc <b>113</b> is of the rewritable type. During the second mode of operation, the first, second, . . . , and n-th information signals are stored into the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) of the track buffer memory <b>119</b> at the respective transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn lower than the predetermined constant transfer rate Rp. The first, second, . . . , and n-th information signals are transmitted from the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) of the track buffer memory <b>119</b> to the optical head <b>114</b> at the predetermined constant transfer rate Rp. The optical head <b>114</b> records the first, second, . . . , and n-th information signals on the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) of the optical disc <b>113</b> on a time sharing basis.

A third mode of operation of the apparatus <b>110</b> is executed in the case where the optical disc <b>113</b> is of the rewritable type. During the third mode of operation, the optical head <b>114</b> reproduces at least one information signal from first one of the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) of the optical disc <b>113</b>. The reproduced information signal is transmitted from the optical head <b>114</b> to the track buffer memory <b>119</b>. The reproduced information signal is stored into the track buffer memory <b>119</b> at the predetermined constant transfer rate Rp. The reproduced information is transmitted from the track buffer memory <b>119</b> at the related transfer rate lower than the predetermined constant transfer rate Rp. During the third mode of operation, another information signal (an information signal to be recorded) is stored into the track buffer memory <b>119</b> at the related transfer rate lower than the predetermined constant transfer rate Rp. The recorded information signal is transmitted from the track buffer memory <b>119</b> to the optical head <b>114</b> at the predetermined constant transfer rate Rp. The optical head <b>114</b> records the transmitted information signal on second one of the first, second, . . . , and n-th areas <b>113</b>(1), <b>113</b>(2), . . . , and <b>113</b>(n) of the optical disc <b>113</b>. The signal reproduction by the optical head <b>114</b> and the signal recording by the optical head <b>114</b> alternate with each other on a time sharing basis.

As previously indicated, the rate of the transfer of the first, second, . . . , and n-th information signals by the optical head <b>114</b> is denoted by “Rp” (Mbps). Regarding the track buffer memory <b>119</b>, the rate of the transfer of the first information signal is denoted by “R1” (Mbps). The rate of the transfer of the second information signal is denoted by “R2” (Mbps). Similarly, the rates of the transfer of the third and later information signals are denoted by “R3”, . . . (Mbps). The rate of the transfer of the n-th information signal is denoted by “Rn” (Mbps). The minimum capacity of the track buffer memory <b>119</b> is denoted by “Ym” (Mbits). The size (the total number of bits) of the first information signal recorded on each of the sub-areas A<b>1</b>, A<b>2</b>, A<b>3</b>, . . . in the first area <b>113</b>(1) of the optical disc <b>113</b> is denoted by “Y1” (Mbits). The size (the total number of bits) of the second information signal recorded on each of the sub-areas B<b>1</b>, B<b>2</b>, B<b>3</b>, . . . in the second area <b>113</b>(2) of the optical disc <b>113</b> is denoted by “Y2” (Mbits). Similarly, the sizes of the third and later information signals are denoted by “Y3”, . . . (Mbits). The size (the total number of bits) of the n-th information signal recorded on each of the sub-areas N<b>1</b>, N<b>2</b>, N<b>3</b>, . . . in the n-th area <b>113</b>(n) of the optical disc <b>113</b> is denoted by “Yn” (Mbits). The seek time of movement of the optical head <b>114</b> from the first area <b>113</b>(1) to the second area <b>113</b>(2) in the optical disc <b>113</b> is denoted by “S1” (s). The seek time of movement of the optical head <b>114</b> from the second area <b>113</b>(2) to the third area <b>113</b>(3) in the optical disc <b>113</b> is denoted by “S2” (s). Similarly, the seek time of movement of the optical head <b>114</b> from present one to next one of the third and later areas is denoted by “Sk” (s) where k=3, 4, 5, . . . . The seek time of movement of the optical head <b>114</b> from the n-th area <b>113</b>(n) to the first area <b>113</b>(1) in the optical disc <b>113</b> is denoted by “Sn” (s).

Each of the seek times S<b>1</b>, S<b>2</b>, . . . , and Sn is equal to a first time interval plus a second time interval. The first time interval starts from the moment at which the optical head <b>114</b> reaches a reproduction end position and suspends the reproduction of an information signal from one area <b>113</b>(1), <b>113</b>(2), . . . , or <b>113</b>(n) in the optical disc <b>113</b>. The first time interval ends and the second time interval starts when the optical head <b>114</b> moves to a next area in the optical disc <b>113</b>. The second time interval continues until the optical head <b>114</b> starts reproducing an information signal from the next area in the optical disc <b>113</b>. During the second time interval, a target address of the next area in the optical disc <b>113</b> is found, and preparations for the reproduction of the information signal therefrom have been made.

The sum ΣRn of the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn for the information signals written into and read out from the track buffer memory <b>119</b> is smaller than the predetermined constant transfer rate Rp related to the optical head <b>114</b>. Thus, the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn, and the predetermined constant transfer rate Rp are in the following relation.

<maths><formula-text><i>Rp</i>>R<b>1</b>+R<b>2</b>+ . . . +<i>Rn</i>  (31)</formula-text></maths>

The recording or playback time T<b>1</b> (S) for which the optical head <b>114</b> continuously records or reproduces the first information signal on or from the first area <b>113</b>(1) of the optical disc <b>113</b> is given as follows.

<maths><formula-text>T<b>1</b>=Y<b>1</b>/<i>Rp</i>  (32)</formula-text></maths>

The recording or playback time T<b>2</b> (S) for which the optical head <b>114</b> continuously records or reproduces the second information signal on or from the second area <b>113</b>(2) of the optical disc <b>113</b> is given as follows.

<maths><formula-text>T<b>2</b>=Y<b>2</b>/<i>Rp</i>  (33)</formula-text></maths>

Similarly, the recording or playback time Tk (S) for which the optical head <b>114</b> continuously records or reproduces the k-th information signal on or from the k-th area <b>113</b>(k) of the optical disc <b>113</b> is given as follows.

<maths><formula-text><i>Tk=Yk/Rp </i>where <i>k=</i>3, 4, 5, . . . </formula-text></maths>

The recording or playback time Tn (S) for which the optical head <b>114</b> continuously records or reproduces the n-th information signal on or from the n-th area <b>113</b>(2) of the optical disc <b>113</b> is given as follows.

<maths><formula-text><i>Tn=Yn/Rp</i>  (34)</formula-text></maths>

Regarding the transfer rates Rp, R<b>1</b>, R<b>2</b>, . . . , and Rn, the following ratio is considered.

<maths><formula-text><i>Rp</i>/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (35)</formula-text></maths>

where “Rp” corresponds to a 1-cycle time during which the first, second, . . . , and n-th information signals are sequentially recorded or reproduced once, and “(Rp−R<b>1</b>−R<b>2</b> . . . −Rn)” corresponds to a seek period in the 1-cycle time.

Regarding the times T<b>1</b>, T<b>2</b>, . . . , and Tn, S<b>1</b>, S<b>2</b>, . . . , and Sn, the following ratio is considered.

<maths><formula-text>(T<b>1</b>+S<b>1</b>+T<b>2</b>+S<b>2</b> . . . +<i>Tn+Sn</i>)/(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)  (36)</formula-text></maths>

where “(T<b>1</b>+S<b>1</b>+T<b>2</b>+S<b>2</b> . . . +Tn+Sn)” corresponds to a 1-cycle time during which the first, second, . . . , and n-th information signals are sequentially recorded or reproduced once, and “(S<b>1</b>+S<b>2</b> . . . +Sn)” corresponds to a total seek period in the 1-cycle time.

The ratio in the relation (35) and the ratio in the relation (36) are equal to each other, and the following relation is available.

<maths><formula-text><i>Rp</i>/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)=(T<b>1</b>+S<b>1</b>+T<b>2</b>+S<b>2</b> . . . +<i>Tn+Sn</i>)/(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)  (37)</formula-text></maths>

The equation (37) is changed into the following version.

<maths><formula-text>(T<b>1</b>+T<b>2</b> . . . +<i>Tn</i>)=(R<b>1</b>+R<b>2</b> . . . +<i>Rn</i>)·(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (38)</formula-text></maths>

Combining the equations (32) and (33) with the equation (38) results in the following equation.

<maths><formula-text>(Y<b>1</b>+Y<b>2</b> . . . +<i>Yn</i>)=<i>Rp</i>·(R<b>1</b>+R<b>2</b> . . . +<i>Rn</i>)·(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (39)</formula-text></maths>

The rate Rp of the transfer of the first, second, . . . , and n-th information signals between the optical disc <b>113</b> and the track buffer memory <b>119</b> is equal to the predetermined constant value. The predetermined constant transfer rate Rp is higher than the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn for the first, second, . . . , and n-th information signals in connection with the track buffer memory <b>119</b>. During the recording of the first, second, . . . , and n-th information signals, the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are decided on the basis of the user's setting (the user's selection). During the playback of the first, second, . . . , and n-th information signals, the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are decided on the basis of the recording conditions stored in the optical disc <b>113</b> as control data. For example, the control data are contained in management information stored in the management area <b>113</b><i>x </i>of the optical disc <b>113</b>. The seek times S<b>1</b>, S<b>2</b>, . . . , and Sn are determined according to the specifications of the apparatus <b>110</b> and the addresses on the optical disc <b>113</b>. To implement continuous recording or continuous playback of the information-signal contents, the sum ΣYn of the size (the total number of bits) Y<b>1</b> of the first information signal on each of the sub-areas in the first area <b>113</b>(1) of the optical disc <b>113</b>, the size (the total number of bits) Y<b>2</b> of the second information signal on each of the sub-areas in the second area <b>113</b>(2) of the optical disc <b>113</b>, . . . , and the size (the total number of bits) Yn of the n-th information signal on each of the sub-areas in the n-th area <b>113</b>(n) of the optical disc <b>113</b> is chosen to satisfy a relation (40) as follows.

<maths><formula-text>(Y<b>1</b>+Y<b>2</b> . . . +<i>Yn</i>)≧<i>Rp</i>·(R<b>1</b>+R<b>2</b> . . . +<i>Rn</i>)·(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (40)</formula-text></maths>

The relation (40) is rewritten as follows.

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)  (41)</formula-text></maths>

where:

<maths><formula-text>Σ<i>Yn</i>=Y<b>1</b>+Y<b>2</b> . . . +<i>Yn</i></formula-text></maths>

<maths><formula-text>Σ<i>Rn</i>=R<b>1</b>+R<b>2</b> . . . +<i>Rn</i></formula-text></maths>

<maths><formula-text>Σ<i>Sn</i>=S<b>1</b>+S<b>2</b> . . . +<i>Sn</i></formula-text></maths>

When each of the seek times S<b>1</b>, S<b>2</b>, . . . , and Sn is set to an allowable seek time S equal to a fixed time taken by the optical head <b>114</b> to move between an innermost part and an outermost part of the optical disc <b>113</b>, the following equation is satisfied.

<maths><formula-text>Σ<i>Sn=n·S</i>  (42)</formula-text></maths>

Combining the equation (42) with the relation (41) results in the following equation.

<maths><formula-text>Σ<i>Yn≧Rp·ΣRn·n·S</i>/(<i>Rp−ΣRn</i>)  (43)</formula-text></maths>

In the case where the optical disc <b>113</b> is of the rewritable DVD type, the allowable seek time S is set to about 1.5 seconds.

The sizes Y<b>1</b>, Y<b>2</b>, . . . , and Yn, and the transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn are in the following relations.

<maths><formula-text>Y<b>1</b>≧<i>Rp</i>·R<b>1</b>·(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (44)</formula-text></maths>

<maths><formula-text>Y<b>2</b>≧<i>Rp</i>·R<b>2</b>·(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (45)</formula-text></maths>

. . .

<maths><formula-text><i>Yn≧Rp·Rn</i>·(S<b>1</b>+S<b>2</b> . . . +<i>Sn</i>)/(<i>Rp</i>−R<b>1</b>−R<b>2</b> . . . −<i>Rn</i>)  (46)</formula-text></maths>

Thus, in the case where the transfer rates Rp, R<b>1</b>, R<b>2</b>, . . . , and Rn and the seek times S<b>1</b>, S<b>2</b>, . . . , and Sn are decided, continuous recording or continuous playback of the contents of the “n” information signals can be implemented when the sizes Y<b>1</b>, Y<b>2</b>, . . . , and Yn are chosen to satisfy the above-indicated relations (40), (41), (43), (44), (45), and (46). The recording or playback times T<b>1</b>, T<b>2</b>, . . . , and Tn are determined as the sizes Y<b>1</b>, Y<b>2</b>, . . . , and Yn and the transfer rates Rp, R<b>1</b>, R<b>2</b>, . . . , and Rn are decided.

In addition, the sum ΣYn of the sizes Y<b>1</b>, Y<b>2</b>, . . . , and Yn, the maximum size of the track buffer memory <b>119</b>, and the empty value and the full value related to each of the first, second, . . . , and n-th areas <b>119</b>(1), <b>119</b>(2), . . . , and <b>119</b>(n) are decided according to the relations (40), (41), (43), (44), (45), and (46).

The minimum capacity Ym of the track buffer memory <b>119</b> satisfies the following relation (47).

<maths><formula-text><i>Ym>Rp·ΣRn·ΣSn</i>/(<i>Rp−ΣRn</i>)  (47)</formula-text></maths>

When each of the seek times S<b>1</b>, S<b>2</b>, . . . , and Sn is set to the allowable seek time S, the relation (47) is rewritten as follows.

<maths><formula-text><i>Ym>Rp·ΣRn·n·S</i>/(<i>Rp−ΣRn</i>)  (48)</formula-text></maths>

It should be noted that a portion of the buffer memory <b>121</b> connected to the audio-video encoding and decoding unit <b>120</b> may be used as a track buffer memory substituting for the track buffer memory <b>119</b>.

In the case where the optical head <b>114</b> is required to record the “n” information signals on the optical disc <b>113</b> on a time sharing basis, conditions of unoccupied portions of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> are detected. Specifically, the management area <b>113</b><i>x </i>in the optical disc <b>113</b> is accessed. Start addresses and end addresses of unoccupied regions are calculated on the basis of the start addresses and the end addresses of data-loaded regions which are stored in the management area <b>113</b><i>x</i>. Then, the sizes and the positions of the unoccupied regions are calculated. For each of the 2-Mbps, 4-Mbps, and 8-Mbps transfer rates concerning the “n” information signals, a decision is made as to whether or not the size of each unoccupied region is sufficient to implement continuous recording. In addition, the seek time of the optical head <b>114</b> is calculated as follows. The difference between addresses is calculated. The movement-corresponding track number is computed on the basis of the address difference by referring to a seek table provided in the program ROM within the system controller <b>122</b>. The computation of the movement-corresponding track number is also based on the fact that the rotation of the optical disc <b>113</b> undergoes CLV control. Given calculation using the movement-corresponding track number and a given coefficient provides a calculated seek time of the optical head <b>114</b>. It should be noted that the seek time of the optical head <b>114</b> may be set to a given value depending on the type of the apparatus <b>110</b> or a standards-based allowable seek time.

Multiple-Signal Playback Mode

A multiple-signal playback mode of operation of the apparatus <b>110</b> is executed in the case where the optical disc <b>113</b> is designed exclusively for playback. During the multiple-signal playback mode of operation, the optical head <b>114</b> reproduces the “n” information signals from the optical disc <b>113</b> on a time sharing basis while the contents of the “n” information signals are continuously played back.

The optical disc <b>113</b> has the first area <b>113</b>(1) divided into the sub-areas on which the blocks of the first information signal are previously recorded respectively. In addition, the optical disc <b>113</b> has the second area <b>113</b>(2) divided into the sub-areas on which the blocks of the second information signal are previously recorded respectively. Similarly, the optical disc <b>113</b> has the third and later areas <b>113</b>(3) . . . on which the third and later information signals are previously recorded. Furthermore, the optical disc <b>113</b> has the n-th area <b>113</b>(n) divided into the sub-areas on which the blocks of the n-th information signal are previously recorded respectively. Each of the blocks of the first information signal has a predetermined size (a predetermined total number of bits) Y<b>1</b>. Each of the blocks of the second information signal has a predetermined size (a predetermined total number of bits) Y<b>2</b>. Similarly, the blocks of the third and later information signals have predetermined sizes Y<b>3</b> . . . . Each of the blocks of the n-th information signal has a predetermined size (a predetermined total number of bits) Yn.

When the multiple-signal playback mode of operation is started, the optical head <b>114</b> reproduces management information from the management area <b>113</b><i>x </i>in the optical disc <b>113</b>. The reproduced management information is transmitted from the optical head <b>114</b> to the system controller <b>122</b>. The system controller <b>122</b> detects the locations and conditions of the sub-areas in the areas <b>113</b>(1)-<b>113</b>(n) from the management information. Generally, the system controller <b>122</b> also derives information of transfer rates R<b>1</b>, R<b>2</b>, . . . , and Rn from the management information. Then, the optical head <b>114</b> is moved to a position corresponding to the sub-area A<b>1</b> in the first area <b>113</b>(1) of the optical disc <b>113</b>. The optical head <b>114</b> reproduces the first information signal from the sub-area A<b>1</b> in the optical disc <b>113</b>. The reproduced first information signal is transmitted from the optical head <b>114</b> to the track buffer memory <b>119</b>, being stored into the first area <b>119</b>(1) in the track buffer memory <b>119</b> at the predetermined constant transfer rate Rp.

As shown in FIG. 23, after the degree of occupancy of the first area <b>119</b>(1) in the track buffer memory <b>119</b> reaches the related empty value, the first information signal is read out from the memory area <b>119</b>(1) toward the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>1</b> and the first information signal is transmitted from the sub-area A<b>1</b> in the optical disc <b>113</b> to the memory area <b>119</b>(1) at the predetermined constant transfer rate Rp. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(1) increases at a rate corresponding to “Rp−R1”.

When the degree of occupancy of the memory area <b>119</b>(1) reaches the related full value, the transmission of the first information signal from the sub-area A<b>1</b> in the optical disc <b>113</b> to the memory area <b>119</b>(1) is suspended. Then, the optical head <b>114</b> is moved to a position corresponding to the sub-area B<b>1</b> in the second area <b>113</b>(2) of the optical disc <b>113</b>. The seek time S<b>1</b> related to this movement of the optical head <b>114</b> is equal to or shorter than 1.5 seconds. The optical head <b>114</b> transmits the second information signal from the sub-area B<b>1</b> in the optical disc <b>113</b> to the second area <b>119</b>(2) of the track buffer memory <b>119</b> at the predetermined constant transfer rate Rp. Even after the degree of occupancy of the memory area <b>119</b>(1) reaches the related full value, the first information signal continues to be read out from the memory area <b>119</b>(1) at the transfer rate R<b>1</b>. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(1) decreases at a rate corresponding to “R1”. The read-out of the first information signal from the memory area <b>119</b>(1) is completed before the optical head <b>114</b> accesses the sub-area A<b>2</b> in the first area <b>113</b>(1) of the optical disc <b>113</b>.

After the degree of occupancy of the second area <b>119</b>(2) in the track buffer memory <b>119</b> reaches the related empty value, the second information signal is read out from the memory area <b>119</b>(2) toward the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>2</b> and the second information signal continues to be transmitted from the sub-area B<b>1</b> in the optical disc <b>113</b> to the memory area <b>119</b>(2) at the predetermined constant transfer rate Rp. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(2) increases at a rate corresponding to “Rp−R2”.

When the degree of occupancy of the memory area <b>119</b>(2) reaches the related full value, the transmission of the second information signal from the sub-area B<b>1</b> in the optical disc <b>113</b> to the memory area <b>119</b>(2) is suspended. Then, the optical head <b>114</b> is moved to a position corresponding to the first sub-area in the third area <b>113</b>(3) of the optical disc <b>113</b>. The seek time S<b>2</b> related to this movement of the optical head <b>114</b> is equal to or shorter than 1.5 seconds. Even after the degree of occupancy of the memory area <b>119</b>(2) reaches the related full value, the second information signal continues to be read out from the memory area <b>119</b>(2) at the transfer rate R<b>2</b>. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(2) decreases at a rate corresponding to “R2”. The read-out of the second information signal from the memory area <b>119</b>(2) is completed before the optical head <b>114</b> accesses the sub-area B<b>2</b> in the second area <b>113</b>(2) of the optical disc <b>113</b>.

The above-mentioned sequence of steps is iterated while the optical head <b>114</b> sequentially reproduces the third and later information signals from the first sub-areas in the third and later areas <b>113</b>(3)-<b>113</b>(n) of the optical disc <b>113</b>. After the reproduction of the n-th information signal from the sub-area N<b>1</b> in the n-th area <b>113</b>(n) of the optical disc <b>113</b> is completed, the optical head <b>114</b> is moved to a position corresponding to the sub-area A<b>2</b> in the first area <b>113</b>(1) of the optical disc <b>113</b>. During a subsequent term, such processes are iterated. Thus, the contents of the “n” information signals are continuously played back while the optical head <b>114</b> sequentially accesses the sub-areas in the areas <b>113</b>(1)-<b>113</b>(n) of the optical disc <b>113</b> in the order as “A1, B1, . . . , N1, A2, B2, . . . , N2, . . . ”. During the multiple-signal playback mode of operation of the apparatus <b>110</b>, the previously-indicated parameters satisfy the relations (31)-(48).

Multiple-Signal Recording Mode

A multiple-signal recording mode of operation of the apparatus <b>110</b> is executed in the case where the optical disc <b>113</b> is of the rewritable type. During the multiple-signal recording mode of operation, the “n” information signals are written into the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> at the transfer rates R<b>1</b>-Rn, respectively. The “n” information signals are transmitted from the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis at the predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>-Rn. The optical head <b>114</b> records the “n” information signals on the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> on a time sharing basis, respectively.

The optical disc <b>113</b> is previously provided with the first area <b>113</b>(1) divided into the sub-areas for storing the respective blocks of the first information signal. The sub-areas in the first area <b>113</b>(1) have the predetermined size Y<b>1</b>. In addition, the optical disc <b>113</b> is previously provided with the second area <b>113</b>(2) divided into the sub-areas for storing the respective blocks of the second information signal. The sub-areas in the second area <b>113</b>(2) have the predetermined size Y<b>2</b>. Similarly, the optical disc <b>113</b> is previously provided with the third and later areas <b>113</b>(3) . . . for storing the third and later information signals. Furthermore, the optical disc <b>113</b> is previously provided with the n-th area <b>113</b>(n) divided into the sub-areas for storing the respective blocks of the n-th information signal. The sub-areas in the n-th area <b>113</b>(n) have the predetermined size Yn. In addition, the optical disc <b>113</b> has the management area <b>113</b><i>x </i>loaded with the management information representing the locations and conditions of the sub-areas in the areas <b>113</b>(1)-<b>113</b>(n). Unoccupied regions in the optical disc <b>113</b> can be detected from the management information.

During the multiple-signal recording mode of operation of the apparatus <b>110</b>, the audio-video encoding and decoding unit <b>120</b> encodes “n” original signals into the “n” information signals respectively. The “n” information signals are transferred from the audio-video encoding and decoding unit <b>120</b> to the track buffer memory <b>119</b> at the rates R<b>1</b>-Rn, respectively. The rates R<b>1</b>-Rn of the transfer of the “n” information signals from the audio-video encoding and decoding unit <b>120</b> to the track buffer memory <b>119</b> can be selected from among different values according to user's operation of the key input unit <b>123</b>. The different values include a transfer rate of 8 Mbps which corresponds to a recording time of 2 hours and a high picture quality, a transfer rate of 4 Mbps which corresponds to a recording time of 4 hours and a slightly high picture quality, and a transfer rate of 2 Mpbs which corresponds to a recording time of 8 hours and a normal picture quality. A transfer rate of 17 Mbps may be added to the candidate values. The “n” information signals are temporarily stored in the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b>, respectively. At an initial stage, the optical head <b>114</b> is in a stand-by state or a kick wait state while being located at a position corresponding to a target track on the optical disc <b>113</b>. The system controller <b>122</b> always monitors the degree of occupancy of each of the memory areas <b>119</b>(1)-<b>119</b>(n) which varies between the related empty value and the related full value under normal conditions. When the degrees of occupancy of the memory areas <b>119</b>(1)-<b>119</b>(n) reach the related full values, the “n” information signals start to be read out from the memory areas <b>119</b>(1)-<b>119</b>(n) on a time sharing basis and at the predetermined constant transfer rate Rp higher than the transfer rates R<b>1</b>-Rn. The optical head <b>114</b> records the “n” read-out information signals on the areas <b>113</b>(1)-<b>113</b>(n) of the optical disc <b>113</b> respectively on a time sharing basis and at the predetermined constant transfer rate Rp. In this way, the continuously recording of the original signals is implemented.

When the multiple-signal recording mode of operation is started, the optical head <b>114</b> reproduces management information from the management area <b>113</b><i>x </i>in the optical disc <b>113</b>. The reproduced management information is transmitted from the optical head <b>114</b> to the system controller <b>122</b>. The system controller <b>122</b> detects unoccupied regions in the areas <b>113</b>(1)-<b>113</b>(n) of the optical disc <b>113</b> from the management information. Then, the optical head <b>114</b> is moved to a position corresponding to the sub-area A<b>1</b> in the first area <b>113</b>(1) of the optical disc <b>113</b> provided that the sub-area A<b>1</b> is found to be unoccupied. On the other hand, the first information signal is transmitted from the audio-video encoding and decoding unit <b>120</b> to the track buffer memory <b>119</b>, and is stored into the first area <b>119</b>(1) of the track buffer memory at the transfer rate R<b>1</b>.

As shown in FIG. 24, after the degree of occupancy of the first area <b>119</b>(1) in the track buffer memory <b>119</b> reaches the related full value, the first information signal is transmitted from the memory area <b>119</b>(1) to the sub-area A<b>1</b> in the optical disc <b>113</b> via the optical head <b>114</b> at the predetermined constant transfer rate Rp and the first information signal is stored into the memory area <b>119</b>(1) from the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>1</b>. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(1) decreases at a rate corresponding to “Rp−R1”.

When the degree of occupancy of the memory area <b>119</b>(1) reaches the related empty value, the transmission of the first information signal from the memory area <b>119</b>(1) to the sub-area A<b>1</b> in the optical disc <b>113</b> is suspended. Then, the optical head <b>114</b> is moved to a position corresponding to the sub-area B<b>1</b> in the second area <b>113</b>(2) of the optical disc <b>113</b> provided that the sub-area B<b>1</b> is found to be unoccupied. The seek time S<b>1</b> related to this movement of the optical head <b>114</b> is equal to or shorter than 1.5 seconds. The second information signal is stored into the second area <b>119</b>(2) of the track buffer memory <b>119</b> from the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>2</b>. Even after the degree of occupancy of the memory area <b>119</b>(1) reaches the related empty value, the first information signal continues to be stored into the memory area <b>119</b>(1) from the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>1</b>. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(1) increases at a rate corresponding to “R1”. The degree of occupancy of the memory area <b>119</b>(1) reaches the related full value before the optical head <b>114</b> accesses the sub-area A<b>2</b> in the first area <b>113</b>(1) of the optical disc <b>113</b>.

After the degree of occupancy of the second area <b>119</b>(2) in the track buffer memory <b>119</b> reaches the related full value, the second information signal is transmitted from the memory area <b>119</b>(2) to the sub-area B<b>1</b> in the optical disc <b>113</b> via the optical head <b>114</b> at the predetermined constant transfer rate Rp and the second information signal continues to be stored into the memory area <b>119</b>(2) from the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>2</b>. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(2) decreases at a rate corresponding to “Rp−R2”.

When the degree of occupancy of the memory area <b>119</b>(2) reaches the related empty value, the transmission of the second information signal from the memory area <b>119</b>(2) to the sub-area B<b>1</b> in the optical disc <b>113</b> is suspended. Then, the optical head <b>114</b> is moved to a position corresponding to the first sub-area in the third area <b>113</b>(3) of the optical disc <b>113</b> provided that the first sub-area is found to be unoccupied. The seek time S<b>2</b> related to this movement of the optical head <b>114</b> is equal to or shorter than 1.5 seconds. Even after the degree of occupancy of the memory area <b>119</b>(2) reaches the related empty value, the second information signal continues to be stored into the memory area <b>119</b>(2) from the audio-video encoding and decoding unit <b>120</b> at the transfer rate R<b>2</b>. Thus, during this stage, the degree of occupancy of the memory area <b>119</b>(2) increases at a rate corresponding to “R2”. The degree of occupancy of the memory area <b>119</b>(2) reaches the related full value before the optical head <b>114</b> accesses the sub-area B<b>2</b> in the second area <b>113</b>(2) of the optical disc <b>113</b>.

The above-mentioned sequence of steps is iterated while the third and later information signals are stored into the third and later areas <b>119</b>(3)-<b>119</b>(n) of the track buffer memory <b>119</b> from the audio-video encoding and decoding unit <b>120</b> at the transfer rates R<b>3</b>-Rn. In addition, the third and later information signals are transmitted from the third and later areas <b>119</b>(3)-<b>119</b>(n) of the track buffer memory <b>119</b> to the optical head <b>114</b> at the predetermined constant transfer rate Rp on a time sharing basis. The optical head <b>114</b> sequentially records the third and later information signals on the first sub-areas in the third and later areas <b>113</b>(3)-<b>113</b>(n) of the optical disc <b>113</b>. After the recording of the n-th information signal on the sub-area N<b>1</b> in the n-th area <b>113</b>(n) of the optical disc <b>113</b> is completed, the optical head <b>114</b> is moved to a position corresponding to the sub-area A<b>2</b> in the first area <b>113</b>(1) of the optical disc <b>113</b> provided that the sub-area A<b>2</b> is found to be unoccupied. During a subsequent term, such processes are iterated. Thus, the “n” original signals inputted into the audio-video encoding and decoding unit <b>120</b> are continuously recorded while the optical head <b>114</b> sequentially accesses the sub-areas in the areas <b>113</b>(1)-<b>113</b>(n) of the optical disc <b>113</b> in the order as “A1, B1, . . . , N1, A2, B2, . . . , N2, . . . ”. During the multiple-signal recording mode of operation of the apparatus <b>110</b>, the previously-indicated parameters satisfy the relations (31)-(48).

In general, after the recording of the “n” information signals on the optical disc <b>113</b> has been completed, information of the transfer rates R<b>1</b>-Rn is recorded on the management area <b>113</b><i>x </i>of the optical disc <b>113</b> via the optical head <b>114</b>.

Signal Recording/Playback Mode

A signal recording/playback mode of operation of the apparatus <b>110</b> is executed in the case where the optical disc <b>113</b> is of the rewritable type. During the signal recording/playback mode of operation, the optical head <b>114</b> reproduces at least one information signal from first one of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> and records at least one information signal on second one of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> on a time sharing basis. The reproduced information signal is transmitted from the optical disc <b>114</b> to the track buffer memory <b>119</b>. The reproduced information signal is written into corresponding one of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> at the predetermined constant transfer rate Rp. The reproduced information signal is transmitted from the track buffer memory <b>119</b> to the audio-video encoding and decoding unit <b>120</b> at corresponding one of the transfer rates R<b>1</b>-Rn. On the other hand, at least one information signal to be recorded is transmitted to the track buffer memory <b>119</b> from the audio-video encoding and decoding unit <b>120</b>. The recorded information signal is written into corresponding one of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> at corresponding one of the transfer rates R<b>1</b>-Rn. The recorded information signal is transmitted from the track buffer memory <b>119</b> to the optical head <b>114</b> at the predetermined constant transfer rate Rp. The optical head <b>114</b> records the transmitted information signal on corresponding one of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b>.

During the signal recording/playback mode of operation, each of the seek times S<b>1</b>-Sn related to the optical head <b>114</b> is equal to or shorter than 1.5 seconds. In addition, the previously-indicated parameters satisfy the relations (31)-(48).

It should be noted that the “n” information signals to be recorded or reproduced may be ranked according to priority. In the case where a seek error occurs or the transfer rates R<b>1</b>-Rn are changed so that the relations (31)-(48) become unsatisfied, low-priority information signals may be discarded or disregarded to maintain continuous recording or continuous playback of the contents of high-priority information signals.

It should be noted that the apparatus <b>110</b> in FIG. 17 may be divided into an optical disc drive, a solid-state memory unit, and another unit. The solid-state memory unit is detachably connected with the optical disc drive. Specifically, the solid-state memory unit is connected with the optical disc drive via a disconnectable connector. The optical disc drive includes the spindle motor <b>111</b>, the turntable <b>112</b>, the optical head <b>114</b>, the driver <b>115</b>, the amplifier unit <b>116</b>, and the servo unit <b>117</b>. The solid-state memory unit includes the signal processor <b>118</b>, the track buffer memory <b>119</b>, and the system controller <b>122</b>. When the solid-state memory unit is disconnected from the optical disc drive, at least one of “n” information signals in the track buffer memory <b>119</b> can be played back via the signal processor <b>118</b> and the audio-video encoding and decoding unit <b>120</b>.

Sixth Embodiment

FIG. 25 shows an information-signal communication apparatus <b>130</b> according to a sixth embodiment of this invention. The apparatus <b>130</b> in FIG. 25 is similar to the apparatus <b>110</b> in FIG. 17 except for design changes indicated hereinafter.

The apparatus <b>130</b> in FIG. 25 includes a spindle motor <b>111</b>, a turntable <b>112</b>, an optical head (an optical pickup) <b>114</b>, a driver <b>115</b>, an amplifier unit <b>116</b>, a servo unit <b>117</b>, a signal processor <b>118</b>, a track buffer memory <b>119</b>, and a system controller <b>122</b>. The devices <b>111</b>, <b>112</b>, <b>114</b>, <b>115</b>, <b>116</b>, <b>117</b>, <b>118</b>, <b>119</b>, and <b>122</b> are connected in a manner similar to that in the apparatus <b>110</b> in FIG. <b>17</b>. The apparatus <b>130</b> in FIG. 25 further includes an ATAPI (AT attachment packet interface) unit <b>131</b>, that is, an interface <b>131</b> of an ATAPI type. The interface <b>131</b> is connected to the signal processor <b>118</b>.

A host computer or an external apparatus <b>132</b> can be connected with the apparatus <b>130</b> in FIG. 25 via the interface <b>131</b>. The external apparatus <b>132</b> includes an audio-video encoding and decoding unit <b>120</b>, a memory <b>121</b>, and a host computer unit <b>132</b>A. The memory <b>121</b> and the host computer unit <b>132</b>A are connected to the audio-video encoding and decoding unit <b>120</b>. The audio-video encoding and decoding unit <b>120</b> can be connected with the signal processor <b>118</b> in the apparatus <b>130</b> via the interface <b>131</b>.

A satellite digital broadcasting reception antenna <b>141</b> is connected to a satellite digital broadcasting decoder <b>142</b>. The satellite digital broadcasting decoder <b>142</b> is connected to a switch <b>143</b>. A switch <b>143</b> is connected to a stream converter <b>144</b>. The switch <b>143</b> is connected to the Internet via a terminal <b>145</b>. The stream converter <b>144</b> can be connected with the signal processor <b>118</b> in the apparatus <b>130</b> via the interface <b>131</b>. The satellite digital broadcasting decoder <b>142</b>, the switch <b>143</b>, the stream converter <b>144</b>, and the host computer unit <b>132</b>A are connected to each other.

In more detail, the ATAPI unit <b>131</b> includes an interface block. The audio-video encoding and decoding unit <b>120</b> includes an interface block which can be connected with the interface block in the ATAPI unit <b>131</b>. The stream converter <b>144</b> includes an interface block which can be connected with the interface block in the ATAPI unit <b>131</b>. The apparatus <b>132</b> can control the apparatus <b>130</b> while using control signals in the Mt. Fuji command system. The host computer unit <b>132</b>A can control the switch <b>143</b>.

In the case where “n” information signals are required to be recorded, the host computer unit <b>132</b>A in the apparatus <b>132</b> transmits information of transfer rates R<b>1</b>-Rn for the “n” information signals (transfer-rate representing flags) to the apparatus <b>130</b> via the audio-video encoding and decoding unit <b>120</b> and the interface <b>131</b>. The audio-video encoding and decoding unit <b>120</b> in the apparatus <b>132</b> transmits the “n” information signals to the signal processor <b>118</b> in the apparatus <b>130</b> via the interface <b>131</b>. In addition, the host computer unit <b>132</b>A in the apparatus <b>132</b> transmits a recording start command signal and a recording start address signal to the apparatus <b>130</b> via the audio-video encoding and decoding unit <b>120</b> and the interface <b>131</b>.

In the case where “n” information signals are required to be reproduced from an optical disc <b>113</b>, the host computer unit <b>132</b>A in the apparatus <b>132</b> transmits a playback start command signal and a disc address signal to the apparatus <b>130</b> via the audio-video encoding and decoding unit <b>120</b> and the interface <b>131</b>. The apparatus <b>130</b> reproduces a signal (for example, control data or management information) from a portion of the optical disc <b>113</b> whose position is designated by the disc address signal. The host computer unit <b>132</b>A in the apparatus <b>132</b> receives the reproduced signal from the apparatus <b>130</b> via the interface <b>131</b> and the audio-video encoding and decoding unit <b>120</b>, and calculates transfer rates R<b>1</b>-Rn on the basis of the reproduced signal. The host computer unit <b>132</b>A in the apparatus <b>132</b> transmits information of the calculated transfer rates R<b>1</b>-Rn (transfer-rate representing flags) to the apparatus <b>130</b> via the audio-video encoding and decoding unit <b>120</b> and the interface <b>131</b>. Then, the apparatus <b>130</b> reproduces the “n” information signals while using the transfer rates R<b>1</b>-Rn.

The interface <b>131</b> may be of an IEEE1394 type rather than the ATAPI type. The interface <b>131</b> may be of a wireless type using a radio signal or a light signal.

It should be noted that the apparatus <b>130</b> in FIG. 25 may be divided into an optical disc drive, a solid-state memory unit, and a second unit. The solid-state memory unit is detachably connected with the optical disc drive and the interface <b>131</b> in the second unit. Specifically, the solid-state memory unit is connected with the optical disc drive and the interface <b>131</b> via disconnectable connectors. The optical disc drive includes the spindle motor <b>111</b>, the turntable <b>112</b>, the optical head <b>114</b>, the driver <b>115</b>, the amplifier unit <b>116</b>, and the servo unit <b>117</b>. The solid-state memory unit includes the signal processor <b>118</b>, the track buffer memory <b>119</b>, and the system controller <b>122</b>. When the solid-state memory unit is disconnected from the optical disc drive, at least one of “n” information signals in the track buffer memory <b>119</b> can be played back via the signal processor <b>118</b> and the audio-video encoding and decoding unit <b>120</b>.

Seventh Embodiment

A seventh embodiment of this invention is similar to the fifth embodiment or the sixth embodiment thereof except for design changes mentioned later.

During a recording mode of operation, the system controller <b>122</b> periodically checks whether or not the relation (41) is satisfied. When the system controller <b>122</b> finds that the relation (41) is not satisfied, the system controller <b>122</b> selects one of first, second, third, and fourth recording procedures and implements the selected recording procedure.

According to the first recording procedure, when the relation (41) is not satisfied, two or more information signals are selected from among “n” information signals. Non-selected information signals are discarded or disregarded. With respect to the selected information signals, a decision is made as to whether or not the relation (41) is satisfied. In the case where the relation (41) is satisfied, the selected information signals are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The selected information signals are transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The optical head <b>114</b> records the selected information signals on corresponding ones of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> respectively. When being recorded, the selected information signals may be weighted in response to the differences among the transfer rates for the selected information signals, the channel position, or the genres of the contents of the selected information signals on an automatic basis or a user's setting basis. The non-selected information signals are inhibited from being stored into the track buffer memory <b>119</b>.

With reference to FIG. 26, four information signals “A”, “B”, “C”, and “D” compose input data. The information signal “A” is divided into blocks A<b>1</b>, A<b>2</b>, . . . . The information signal “B” is divided into blocks B<b>1</b>, B<b>2</b>, . . . . The information signal “C” is divided into blocks C<b>1</b>, C<b>2</b>, . . . . The information signal “D” is divided into blocks D<b>1</b>, D<b>2</b>, . . . . The blocks of the four information signals are multiplexed into the input data in the order as “A1, B1, C1, D1, A2, B2, . . . ”.

According to the first recording procedure, when the relation (41) is not satisfied, two information signals “A” and “B” are selected from among the four information signals. Regarding the selected information signals “A” and “B”, a decision is made as to whether or not the relation (41) is satisfied. In the case where the relation (41) is satisfied, the selected information signals are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The non-selected information signals “C” and “D” are inhibited from being stored into the track buffer memory <b>119</b>. The selected information signals “A” and “B” are alternately transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The optical head <b>114</b> records the selected information signals “A” and “B” on corresponding ones of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> respectively. Specifically, the optical head <b>114</b> records the block A<b>1</b> of the information signal “A” on first one of the disc areas <b>113</b>(1)-<b>113</b>(n). Then, the optical head <b>114</b> executes seek and moves from first one to second one of the disc areas <b>113</b>(1)-<b>113</b>(n). The optical head <b>114</b> records the block B<b>1</b> of the information signal “B” on second one of the disc areas <b>113</b>(1)-<b>113</b>(n). Then, the optical head <b>114</b> executes seek and moves from second one to first one of the disc areas <b>113</b>(1)-<b>113</b>(n). The optical head <b>114</b> records the block A<b>2</b> of the information signal “A” on first one of the disc areas <b>113</b>(1)-<b>113</b>(n). Such steps are reiterated. Accordingly, the blocks A<b>1</b>, A<b>2</b>, . . . of the information signal “A” are sequentially stored into first one of the disc areas <b>113</b>(1)-<b>113</b>(n). The blocks B<b>1</b>, B<b>2</b>, . . . of the information signal “B” are sequentially stored into second one of the disc areas <b>113</b>(1)-<b>113</b>(n).

According to the second recording procedure, when the relation (41) is not satisfied, two or more information signals are selected from among “n” information signals. The selected information signals are referred to as the first selected information signals. Non-selected information signals are discarded or disregarded. Two of the first selected information signals are combined into one selected information signal. This selected information signal and the remaining first selected information signal or signals are referred to as the second selected information signals. With respect to the second selected information signals, a decision is made as to whether or not the relation (41) is satisfied. In the case where the relation (41) is satisfied, the first selected information signals are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The first selected information signals are transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis while two of the first selected information signals are combined into one selected information signal. Thus, the optical head <b>114</b> receives the second selected information signals from the track buffer memory <b>119</b>. The optical head <b>114</b> records the second selected information signals on ones of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b> respectively.

With reference to FIG. 27, four information signals “A”, “B”, “C”, and “D” compose input data. The information signal “A” is divided into blocks A<b>1</b>, A<b>2</b>, . . . . The information signal “B” is divided into blocks B<b>1</b>, B<b>2</b>, . . . . The information signal “C” is divided into blocks C<b>1</b>, C<b>2</b>, . . . . The information signal “D” is divided into blocks D<b>1</b>, D<b>2</b>, . . . . The blocks of the four information signals are multiplexed into the input data in the order as “A1, B1, C1, D1, A2, B2, . . . ”.

According to the second recording procedure, when the relation (41) is not satisfied, three information signals “A”, “B”, and “C” are selected from among the four information signals. The selected information signals “B” and “C” are combined into and handled as one selected information signal “B+C”. Regarding the selected information signals “A” and “B+C”, a decision is made as to whether or not the relation (41) is satisfied. In the case where the relation (41) is satisfied, the selected information signals “A”, “B”, and “C” (the selected information signals “A” and “B+C”) are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The non-selected information signal “D” is inhibited from being stored into the track buffer memory <b>119</b>. The selected information signals “A” and “B+C” are alternately transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The optical head <b>114</b> records the selected information signals “A” and “B+C” on ones of the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b>. Specifically, the optical head <b>114</b> records the block A<b>1</b> of the information signal “A” on first one of the disc areas <b>113</b>(1)-<b>113</b>(n). Then, the optical head <b>114</b> executes seek and moves from first one to second one of the disc areas <b>113</b>(1)-<b>113</b>(n). The optical head <b>114</b> records the blocks B<b>1</b> and C<b>1</b> of the information signals “B” and “C” on second one of the disc areas <b>113</b>(1)-<b>113</b>(n). Then, the optical head <b>114</b> executes seek and moves from second one to first one of the disc areas <b>113</b>(1)-<b>113</b>(n). The optical head <b>114</b> records the block A<b>2</b> of the information signal “A” on first one of the disc areas <b>113</b>(1)-<b>113</b>(n). Such steps are reiterated. Accordingly, the blocks A<b>1</b>, A<b>2</b>, of the information signal “A” are sequentially stored into first one of the disc areas <b>113</b>(1)-<b>113</b>(n). The blocks B<b>1</b>, C<b>1</b>, B<b>2</b>, C<b>2</b>, of the information signals “B” and “C” are sequentially stored into second one of the disc areas <b>113</b>(1)-<b>113</b>(n). This design results in a reduction of the total seek time related to the optical head <b>114</b>.

According to the third recording procedure, when the relation (41) is not satisfied, “n” information signals are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The “n” information signals are transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The optical head <b>114</b> records the “n” information signals on one common area (for example, one of the areas <b>113</b>(1)-<b>113</b>(n)) in the optical disc <b>113</b>. Since the optical head <b>114</b> does not move among the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b>, the total seek time related to the optical head <b>114</b> can be reduced.

With reference to FIG. 28, four information signals “A”, “B”, “C”, and “D” compose input data. The information signal “A” is divided into blocks A<b>1</b>, A<b>2</b>, . . . . The information signal “B” is divided into blocks B<b>1</b>, B<b>2</b>, . . . . The information signal “C” is divided into blocks C<b>1</b>, C<b>2</b>, . . . . The information signal “D” is divided into blocks D<b>1</b>, D<b>2</b>, . . . . The blocks of the four information signals are multiplexed into the input data in the order as “A1, B1, C1, D1, A2, B2, . . . ”.

According to the third recording procedure, when the relation (41) is not satisfied, the four information signals “A”, “B”, “D”, and “D” are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The four information signals “A”, “B”, “D”, and “D” are transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The optical head <b>114</b> records the four information signals “A”, “B”, “D”, and “D” on one common area (for example, one of the areas <b>113</b>(1)-<b>113</b>(n)) in the optical disc <b>113</b>. Specifically, the optical head <b>114</b> sequentially records the blocks of the information signals “A”, “B”, “D”, and “D” on the common disc area in the order as “A1, B1, C1, D1, A2, B2, ”.

According to the fourth recording procedure, when the relation (41) is not satisfied, “n” information signals are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. Each of the memory areas <b>119</b>(1)-<b>119</b>(n) can store two or more blocks of the related information signal. Plural block cycles of the “n” information signals are held in the track buffer memory <b>119</b>. The “n” information signals are transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The order in which the blocks of the “n” information signals are read out from the track buffer memory <b>119</b> differs from that occurring in the writing into the track buffer memory <b>119</b>. In other words, the blocks of the “n” information signals are rearranged by the track buffer memory <b>119</b>. The optical head <b>114</b> records the “n” information signals on one common area (for example, one of the areas <b>113</b>(1)-<b>113</b>(n)) in the optical disc <b>113</b>. Since the optical head <b>114</b> does not move among the areas <b>113</b>(1)-<b>113</b>(n) in the optical disc <b>113</b>, the total seek time related to the optical head <b>114</b> can be reduced.

With reference to FIG. 29, four information signals “A”, “B”, “C”, and “D” compose input data. The information signal “A” is divided into blocks A<b>1</b>, A<b>2</b>, . . . . The information signal “B” is divided into blocks B<b>1</b>, B<b>2</b>, . . . . The information signal “C” is divided into blocks C<b>1</b>, C<b>2</b>, . . . . The information signal “D” is divided into blocks D<b>1</b>, D<b>2</b>, . . . . The blocks of the four information signals are multiplexed into the input data in the order as “A1, B1, C1, D1, A2, B2, . . . ”.

According to the fourth recording procedure, when the relation (41) is not satisfied, the four information signals “A”, “B”, “C”, and “D” are stored into corresponding ones of the areas <b>119</b>(1)-<b>119</b>(n) in the track buffer memory <b>119</b> respectively. The blocks of the four information signals “A”, “B”, “D”, and “D” are sequentially written into the track buffer memory <b>119</b> in the order as “A1, B1, C1, D1, A2, B2, . . . ”. Plural block cycles of the “n” information signals are held in the track buffer memory <b>119</b>. The four information signals “A”, “B”, “D”, and “D” are transferred from the track buffer memory <b>119</b> to the optical head <b>114</b> on a time sharing basis. The track buffer memory <b>119</b> rearranges the blocks of the four information signals “A”, “B”, “D”, and “D”. Specifically, the blocks of the four information signals “A”, “B”, “D”, and “D” are sequentially read out from the track buffer memory <b>119</b> in the order as “A1, A2, B1, B2, C1, C2, D1, D2, A3, A4, . . . ”. The optical head <b>114</b> records the four information signals “A”, “B”, and “D” on one common area (for example, one of the areas <b>113</b>(1)-<b>113</b>(n)) in the optical disc <b>113</b>. Specifically, the optical head <b>114</b> sequentially records the blocks of the information signals “A”, “B”, “D”, and “D” on the common disc area in the order as “A1, A2, B1, B2, C1, C2, D1, D2, A3, A4, . . . ”.

One recording procedure is selected from among the first, second, third, and fourth recording procedures in response to the result of calculation concerning the relation (41) or in response to user's requirement. Conditions of the selection include the following conditions {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)}, {circle around (5)}, and {circle around (6)}.

{circle around (1)} Regarding the “n” information signals, a decision is made as to whether or not the relation (41) is satisfied. When it is decided that the relation (41) is not satisfied, at least two of the “n” information signals are selected. Regarding the selected information signals, a decision is made as to whether or not the relation (41) is satisfied. When it is decided that the relation (41) is satisfied, the first or second recording procedure is selected. On the other hand, when it is decided that the relation (41) is not satisfied, the third or fourth recording procedure is selected.

{circle around (2)} At an initial stage, the user selects one from among the first, second, third, and fourth recording procedures by operating the key input unit <b>123</b>. For example, in the case where the first recording procedure is initially selected, a decision is made as to whether or not the relation (41) is satisfied. When it is decided that the relation (41) is satisfied, the system controller <b>122</b> controls the display <b>125</b> via the audio-video encoding and decoding unit <b>120</b> and the NTSC encoder <b>124</b> to indicate that the first, second, third, and fourth recording procedures are selectable. Then, the user finally selects one from among the first, second, third, and fourth recording procedures. On the other hand, when it is decided that the relation (41) is not satisfied, the system controller <b>122</b> controls the display <b>125</b> via the audio-video encoding and decoding unit <b>120</b> and the NTSC encoder <b>124</b> to indicate that the third and fourth recording procedures are selectable. Then, the user finally selects one from among the third and fourth recording procedures.

{circle around (3)} One recording procedure is automatically selected from among the first, second, third, and fourth recording procedures in response to the types of the “n” information signals or the types of the signal sources. When the “n” information signals are fed from the audio-video encoding and decoding unit <b>120</b>, the first or second recording procedure is selected. When the “n” information signals are “n” compression-resultant information signals composing a transport stream signal and transmitted from the satellite or the Internet, the third or fourth recording procedure is selected. The signal recording may be responsive to the differences among the transfer rates for the information signals, the channel position, or the genres of the contents of the information signals on a user's setting basis.

{circle around (4)} When the apparatus is driven by an AC power supply, the first or second recording procedure is selected. When the apparatus is driven by a battery, the third or fourth recording procedure is selected. The track buffer memory <b>119</b> may be replaceable. When the capacity of the track buffer memory <b>119</b> exceeds a reference value, the first or second recording procedure is selected. When the capacity of the track buffer memory <b>119</b> does not exceed the reference value, the third or fourth recording procedure is selected.

{circle around (5)} The system controller <b>122</b> detects the type of the optical disc <b>113</b>. When the optical disc <b>113</b> is a DVD-RAM, the first or second recording procedure is selected. When the optical disc <b>113</b> is a DVD-RW, the third or fourth recording procedure is selected.

{circle around (6)} The management information is reproduced from the management area <b>113</b><i>x </i>in the optical disc <b>113</b>. The system controller <b>122</b> decides the conditions of unoccupied regions in the optical disc <b>113</b> on the basis of the reproduced management information. In the presence of unoccupied regions greater in size than a reference value, the first or second recording procedure is selected. In the absence of such great unoccupied regions, the third or fourth recording procedure is selected.

Eighth Embodiment

FIG. 30 shows an information-signal recording and reproducing apparatus <b>10</b>F according to an eighth embodiment of this invention. The apparatus <b>10</b>F in FIG. 30 is similar to the apparatus <b>10</b>A in FIG. 1 except for design changes indicated hereinafter.

The apparatus <b>10</b>F in FIG. 30 includes an NTSC encoder <b>224</b> and a display <b>225</b>. The NTSC encoder <b>224</b> is connected to an audio-video encoding and decoding unit <b>20</b>. The display <b>225</b> is connected to the NTSC encoder <b>224</b>. The apparatus <b>10</b>F in FIG. 30 includes a system controller <b>22</b>F which replaces the system controller <b>22</b> (see FIG. <b>1</b>). Original information signals for a first information signal “A” and a second information signal “B” can be fed to the audio-video encoding and decoding unit <b>20</b> via input terminals <b>226</b> and <b>227</b>, respectively.

During a playback mode of operation of the apparatus <b>10</b>F, the audio-video encoding and decoding unit <b>20</b> outputs an analog audio signal and an analog video signal to the NTSC converter <b>224</b>. The analog audio signal passes through the NTSC converter <b>224</b> before being applied to loudspeakers provided in the body of the display <b>225</b>. The NTSC converter <b>224</b> changes the analog video signal into a corresponding NTSC video signal. The NTSC converter <b>224</b> outputs the NTSC video signal to the display <b>225</b>.

The apparatus <b>10</b>F operates on an optical disc <b>13</b>F. As shown in FIG. 31, an innermost portion or an inner portion of the optical disc <b>13</b>F has a management area <b>13</b><i>c </i>for storing management information. As shown in FIG. 32, the management area <b>13</b><i>c </i>is divided into separate sub-areas which are given addresses C<b>1</b>, C<b>2</b>, C<b>3</b>, . . . , respectively. Thus, the sub-areas in the management area <b>13</b><i>c </i>are also referred to as the sub-areas C<b>1</b>, C<b>2</b>, C<b>3</b>, . . . . In the case where first areas <b>13</b><i>a </i>and second areas <b>13</b><i>b </i>of the optical disc <b>13</b>F store a first information signal “A” and a second information signal “B”, the management area <b>13</b><i>c </i>is loaded with management information including copyright information, title information, signals representative of transfer rates Ra and Rb, and signals representative of start addresses and end addresses for the first and second information signals “A” and “B”. In the case where the first areas <b>13</b><i>a </i>and the second areas <b>13</b><i>b </i>are unoccupied and do not store the first and second information signals “A” and “B”, the management area <b>13</b><i>c </i>is loaded with management information including signals representative of the start addresses and the end addresses of the unoccupied regions (the unoccupied areas).

In the case where the apparatus <b>10</b>F is required to record the first and second information signals “A” and “B” on the optical disc <b>13</b>F, the system controller <b>22</b>F operates to read out management information from the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F. The system controller <b>22</b>F detects conditions of unoccupied regions in the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b>F by referring to the read-out management information.

Also, in the case where the apparatus <b>10</b>F is required to record one of the first and second information signals “A” and “B” on the optical disc <b>13</b>F and to reproduce the other information signal from the optical disc <b>13</b>F, the system controller <b>22</b>F operates to read out management information from the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F. The system controller <b>22</b>F detects conditions of unoccupied regions in ones of the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b>F by referring to the read-out management information.

Specifically, the system controller <b>22</b>F detects the start addresses and the end addresses of unoccupied regions from the start addresses and the end addresses of data-loaded regions which are stored in the management area <b>13</b><i>c</i>. The system controller <b>22</b>F calculates the sizes of the unoccupied regions from the intervals between the start addresses and the end addresses of the data-loaded regions. The system controller <b>22</b>F stores data representative of the detected positions (the detected start addresses and the detected end addresses) and the calculated sizes of the unoccupied regions into an internal memory. For each of the 2-Mbps, 4-Mbps, and 8-Mbps transfer rates concerning the first and second information signals “A” and “B”, the system controller <b>22</b>F decides whether or not the size of each unoccupied region is sufficient to implement continuous recording or continuous recording/playback. In addition, the system controller <b>22</b>F calculates the seek time of an optical head <b>14</b> as follows. The difference between addresses is calculated. The movement-corresponding track number is computed on the basis of the address difference by referring to a seek table provided in the program ROM within the system controller <b>22</b>F. The computation of the movement-corresponding track number is also based on the fact that the rotation of the optical disc <b>13</b>F undergoes CLV control. Given calculation using the movement-corresponding track number and a given coefficient provides a calculated seek time of the optical head <b>14</b>. It should be noted that the seek time of the optical head <b>14</b> may be set to a given value depending on the type of the apparatus <b>10</b>F or a standards-based allowable seek time.

When the recording of only the information signal “A” is considered and hence the terms related to the information signal “B” are nullified, the previously-indicated relations (9) and (19) are changed into the following relations.

<maths><formula-text><i>Ya≧Rp·Ra</i>·(<i>Tab+Tba</i>)/(<i>Rp−Ra</i>)  (51)</formula-text></maths>

<maths><formula-text><i>Ya≧</i>2<i>·Rp·Ra·Tmax</i>/(<i>Rp−Ra</i>)  (52)</formula-text></maths>

Preferably, the relations (51) and (52) are satisfied to provide the continuity of the contents of the information signal “A” recorded on the unoccupied regions in the optical disc <b>13</b>F. The program ROM in the system controller <b>22</b>F may store a table of the results of previously-executed calculations of the relations (51) and (52). In this case, the table is accessed when the conditions determined by the relations (51) and (52) are required to be detected.

Regarding the recording of only the information signal “A” (only one of the information signals “A” and “B”), the system controller <b>22</b>F calculates the total size of the unoccupied regions in the optical disc <b>13</b>F. For each of the 2-Mbps, 4-Mbps, and 8-Mbps transfer rates, the system controller <b>22</b>F calculates the recording time (or the recording capacity). For each of the 2-Mbps, 4-Mbps, and 8-Mbps transfer rates, the system controller <b>22</b>F calculates the total size of usable portions of the unoccupied regions in the optical disc <b>13</b>F. For each of the 2-Mbps, 4-Mbps, and 8-Mbps transfer rates, the system controller <b>22</b>F calculates the region use efficiency (%) which is equal to the ratio between the total size of the unoccupied regions and the total size of usable portions of the unoccupied regions in the optical disc <b>13</b>F. The system controller <b>22</b>F controls the display <b>225</b> via the audio-video encoding and decoding unit <b>20</b> and the NTSC encoder <b>224</b> to indicate the calculated total size of the unoccupied regions in the optical disc <b>13</b>F, the calculated recording times, the total sizes of usable portions of the unoccupied regions in the optical disc <b>13</b>F, and the calculated region use efficiencies as shown in FIG. <b>33</b>.

During a recording mode of operation of the apparatus <b>10</b>F, a first information signal “A” is inputted into a first area <b>19</b><i>a </i>in a track buffer memory <b>19</b> at a transfer rate Ra while a second information signal “B” is inputted into a second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at a transfer rate Rb. The first and second information signals “A” and “B” are transmitted from the track buffer memory <b>19</b> to the optical head <b>14</b> on a time sharing basis and at a predetermined constant transfer rate Rp higher than the transfer rates Ra and Rb. The optical head <b>14</b> records the first and second information signals “A” and “B” on unoccupied regions in the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b>F. At an initial stage of the recording mode of operation, the system controller <b>22</b>F enables the optical head <b>14</b> to reproduce management information from the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F. The system controller <b>22</b>F detects the conditions of the unoccupied regions in the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b>F by referring to the reproduced management information. The system controller <b>22</b>F decides whether or not the continuously and simultaneously recording of the contents of the first and second information signals “A” and “B” can be implemented on the basis of the detected conditions of the unoccupied regions and the previously-indicated relation (9) or (19). When the system controller <b>22</b>F decides that the continuously and simultaneously recording of the contents of the first and second information signals “A” and “B” can be implemented, the actually recording of the information signals “A” and “B” on the optical disc <b>13</b>F is started.

During a recording/playback mode of operation of the apparatus <b>10</b>F, the optical head <b>14</b> reproduces a first information signal “A” from the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>F. The first information signal “A” is stored into the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> from the optical head <b>14</b> at the predetermined constant transfer rate Rp. The first information signal “A” is transmitted from the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra. On the other hand, a second information signal “B” is inputted into the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the transfer rate Rb. The second information signal “B” is transmitted from the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The optical head <b>14</b> records the second information signal “B” on unoccupied regions in the second areas <b>13</b><i>b </i>of the optical disc <b>13</b>F. The optical head <b>14</b> implements the reproduction of the first information signal “A” and the recording of the second information signal “B” on a time sharing basis. At an initial stage of the recording/playback mode of operation, the system controller <b>22</b>F enables the optical head <b>14</b> to reproduce management information from the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F. The system controller <b>22</b>F detects the conditions of the unoccupied regions in the second areas <b>13</b><i>b </i>of the optical disc <b>13</b>F by referring to the reproduced management information. The system controller <b>22</b>F decides whether or not the playback of the contents of the first information signal “A” and the recording of the contents of the second information signal “B” can be continuously and simultaneously implemented on the basis of the detected conditions of the unoccupied regions and the previously-indicated relation (9) or (19). When the system controller <b>22</b>F decides that the playback of the contents of the first information signal “A” and the recording of the contents of the second information signal “B” can be continuously and simultaneously implemented, the actually playback of the first information signal “A” and the actually recording of the second information signal “B” are started.

For example, the system controller <b>22</b>F executes the calculations and the decisions regarding the relation (9) or (19) each time the recording mode of operation or the recording/playback mode of operation is implemented. The program ROM in the system controller <b>22</b>F may store a table of the results of previously-executed calculations of the relation (9) or (19). In this case, the table is accessed when the conditions determined by the relation (9) or (19) are required to be detected.

When the sum of the transfer rates Ra and Rb for the first and second information signals “A” and “B” is greater than the predetermined constant transfer rate Rp in the relation (9) or (19), it is difficult to implement the continuously and simultaneously recording of the contents of the first and second information signals “A” and “B”. In addition, it is difficult to continuously and simultaneously implement the playback of the contents of the first information signal “A” and the recording of the contents of the second information signal “B”. In these cases, the system controller <b>22</b>F controls the display <b>225</b> via the audio-video encoding and decoding unit <b>20</b> and the NTSC encoder <b>224</b> to indicate the related difficulty.

Regarding the recording of the first and second information signals “A” and “B”, the system controller <b>22</b>F executes the following calculations for each of the first and second information signals “A” and “B”. Specifically, the system controller <b>22</b>F calculates the total size of the unoccupied regions in the optical disc <b>13</b>F. For each of the 2-Mbps, 4-Mbps, 8-Mbps, and 17-Mbps transfer rates, the system controller <b>22</b>F calculates the recording time (or the recording capacity). For each of the 2-Mbps, 4-Mbps, 8-Mbps, and 17-Mbps transfer rates, the system controller <b>22</b>F calculates the total size of usable portions of the unoccupied regions in the optical disc <b>13</b>F. For each of the 2-Mbps, 4-Mbps, 8-Mbps, and 17-Mbps transfer rates, the system controller <b>22</b>F calculates the region use efficiency (%) which is equal to the ratio between the total size of the unoccupied regions and the total size of usable portions of the unoccupied regions in the optical disc <b>13</b>F. The system controller <b>22</b>F controls the display <b>225</b> via the audio-video encoding and decoding unit <b>20</b> and the NTSC encoder <b>224</b> to indicate the calculated total size of the unoccupied regions in the optical disc <b>13</b>F, the calculated recording times, the calculated total sizes of usable portions of the unoccupied regions in the optical disc <b>13</b>F, and the calculated region use efficiencies. An example of this indication is shown in FIG. 34 where only the calculated items available at a transfer rate Ra of 8 Mbps are displayed. In the case where Ra=8 Mbps and Rb=17 Mbps, neither the relation (9) nor the relation (19) is satisfied so that the continuously and simultaneously recording of the contents of the first and second information signals “A” and “B” is difficult or impossible. In this case, the system controller <b>22</b>F controls the display <b>225</b> via the audio-video encoding and decoding unit <b>20</b> and the NTSC encoder <b>224</b> to indicate “recording impossible” as shown in FIG. <b>34</b>.

Regarding the playback of the first information signal “A” and the recording of the second information signal “B”, the system controller <b>22</b>F calculates the total size of the unoccupied regions in the second areas <b>13</b><i>b </i>of the optical disc <b>13</b>F. For each of the 2-Mbps, 4-Mbps, 8-Mbps, and 17-Mbps transfer rates, the system controller <b>22</b>F calculates the recording time (or the recording capacity). For each of the 2-Mbps, 4-Mbps, 8-Mbps, and 17-Mbps transfer rates, the system controller <b>22</b>F calculates the total size of usable portions of the unoccupied regions in the second areas <b>13</b><i>b </i>of the optical disc <b>13</b>F. For each of the 2-Mbps, 4-Mbps, 8-Mbps, and 17-Mbps transfer rates, the system controller <b>22</b>F calculates the region use efficiency (%) which is equal to the ratio between the total size of the unoccupied regions and the total size of usable portions of the unoccupied regions in the optical disc <b>13</b>F. The system controller <b>22</b>F controls the display <b>225</b> via the audio-video encoding and decoding unit <b>20</b> and the NTSC encoder <b>224</b> to indicate the calculated total size of the unoccupied regions in the optical disc <b>13</b>F, the calculated recording times, the calculated total sizes of usable portions of the unoccupied regions in the optical disc <b>13</b>F, and the calculated region use efficiencies. An example of this indication is shown in FIG. 35 where only the calculated items available at a transfer rate Ra of 8 Mbps are displayed. In the case where Ra=8 Mbps and Rb=17 Mbps, neither the relation (9) nor the relation (19) is satisfied so that it is difficult to continuously and simultaneously implement the playback of the contents of the first information signal “A” and the recording of the contents of the second information signal “B”. In this case, the system controller <b>22</b>F controls the display <b>225</b> via the audio-video encoding and decoding unit <b>20</b> and the NTSC encoder <b>224</b> to indicate “recording impossible” as shown in FIG. <b>35</b>.

The on-display indications in FIGS. 33, <b>34</b>, and <b>35</b> may be modified as follows. The calculated total sizes of usable portions of the unoccupied regions in the optical disc <b>13</b>F may be omitted from the indications. The transfer rates may be replaced by “high picture quality”, “slightly high picture quality”, and “normal picture quality”. The transfer rates may be replaced by “2-hour recording mode”, “4-hour recording mode”, and “8-hour recording mode”.

Generally, the user operates a key input unit <b>23</b> and thereby selects the desired values of the transfer rates Ra and Rb in consideration of the items indicated on the display <b>225</b>. During a later stage of operation of the apparatus <b>10</b>F, the actual values of the transfer rates Ra and Rb are equalized to the desired values thereof. In the absence of user's selection of the transfer rates Ra and Rb, the highest values of the transfer rates Ra and Rb are automatically set as the desired values thereof.

Two-Signal Recording Mode

The system controller <b>22</b>F operates in accordance with a program stored in its internal ROM. FIG. 36 is a flowchart of a segment of the program which relates to a two-signal recording mode of operation of the apparatus <b>10</b>F. The program segment in FIG. 36 is started in response to a two-signal-recording start command signal fed from the key input unit <b>23</b>. In this case, the optical disc <b>13</b>F is of the rewritable type.

With reference to FIG. 36, a first step S<b>252</b> of the program segment controls the optical head <b>14</b> to reproduce management information from the management area <b>13</b><i>c </i>in the optical disc <b>13</b>F.

A step S<b>253</b> following the step S<b>252</b> searches for unoccupied regions in the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b>F by referring to address information contained in the reproduced management information. The step S<b>253</b> decides whether or not the continuously and simultaneously recording of the contents of first and second information signals “A” and “B” can be implemented on the basis of the conditions of the unoccupied regions and the previously-indicated relation (9) or (19). The step S<b>253</b> indicates the result of the decision on the display <b>225</b>. When it is decided that the continuously and simultaneously recording of the contents of the first and second information signals “A” and “B” can be implemented, the program advances from the step S<b>253</b> to a step S<b>254</b>.

The step S<b>254</b> decides whether or not the optical head <b>14</b> has reached a target position on the optical disc <b>13</b>F. Initially, the target position corresponds to first one A<b>1</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>F. When the optical head <b>14</b> has not reached the target position yet, the step S<b>254</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>254</b> to a step S<b>255</b>.

The step S<b>255</b> stores the first information signal “A”, which is outputted from the audio-video encoding and decoding unit <b>20</b>, into the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> at the transfer rate Ra.

A step S<b>256</b> following the step S<b>255</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>256</b> to the step S<b>255</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>256</b> to a step S<b>257</b>.

The step S<b>257</b> transfers the first information signal “A” from the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The step S<b>257</b> enables the optical head <b>14</b> to record the first information signal “A” on the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>F at the predetermined constant transfer rate Rp.

A step S<b>258</b> following the step S<b>257</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>258</b> to the step S<b>257</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>258</b> to a step S<b>259</b>.

The step S<b>259</b> forces the optical head <b>14</b> to suspend the recording of the first information signal “A” on the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>F.

A step S<b>260</b> subsequent to the step S<b>259</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, first one B<b>1</b> of the second areas <b>13</b><i>b </i>in the optical disc <b>13</b>F. After the step S<b>260</b>, the program advances to a step S<b>261</b>.

The step S<b>261</b> decides whether or not the optical head <b>14</b> has reached the target position on the optical disc <b>13</b>F. When the optical head <b>14</b> has not reached the target position yet, the step S<b>261</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>261</b> to a step S<b>262</b>.

In this way, the optical head <b>14</b> moves from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b </i>in the optical disc <b>13</b>F. The seek time Tab related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

The step S<b>262</b> stores the second information signal “B”, which is outputted from the audio-video encoding and decoding unit <b>20</b>, into the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the transfer rate Rb.

A step S<b>263</b> following the step S<b>262</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>263</b> to the step S<b>262</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>263</b> to a step S<b>264</b>.

The step S<b>264</b> transfers the second information signal “B” from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The step S<b>264</b> enables the optical head <b>14</b> to record the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>F at the predetermined constant transfer rate Rp.

A step S<b>265</b> following the step S<b>264</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>265</b> to the step S<b>264</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>265</b> to a step S<b>266</b>.

The step S<b>266</b> forces the optical head <b>14</b> to suspend the recording of the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>F.

A step S<b>267</b> subsequent to the step S<b>266</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, second one A<b>2</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>F. After the step S<b>267</b>, the program returns to the step S<b>254</b>.

Thus, the optical head <b>14</b> moves from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a </i>in the optical disc <b>13</b>F. The seek time Tba related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

During the repetitive execution of the program segment in FIG. 36, the target position of the optical head <b>14</b> is sequentially set into correspondence with the first and second areas A<b>1</b>, B<b>1</b>, A<b>2</b>, B<b>2</b>, A<b>3</b>, B<b>3</b>, . . . in the optical disc <b>13</b>F. Therefore, the optical head <b>14</b> alternately records the first information signal “A” and the second information signal “B” on the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b> in the order as “A1, B1, A2, B2, A3, B3, . . . ”.

Preferably, the step S<b>259</b> or the step S<b>266</b> is followed by a step which decides whether or not both the recording of the first information signal “A” on the optical disc <b>13</b>F and the recording of the second information signal “B” thereon are required to be suspended. In this case, when both the recording of the first information signal “A” on the optical disc <b>13</b>F and the recording of the second information signal “B” thereon are required to be suspended, the optical head <b>14</b> is controlled to implement the required suspension of recording.

After the recording of the first and second information signals “A” and “B” on the optical disc <b>13</b>F has been completed, information representing the addresses of the first and second information signals “A ” and “B” on the optical disc <b>13</b>F is recorded on the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F. In addition, information representing the transfer rates Ra and Rb for the first and second information signals “A” and “B” may be recorded on the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F.

Signal Recording/Playback Mode

The system controller <b>22</b>F operates in accordance with the program stored in its internal ROM. FIG. 37 is a flowchart of a segment of the program which relates to a signal recording/playback mode of operation of the apparatus <b>10</b>F. The program segment in FIG. 37 is started in response to a signal-recording/playback start command signal fed from the key input unit <b>23</b>. In this case, the optical disc <b>13</b>F is of the rewritable type.

With reference to FIG. 37, a first step S<b>272</b> of the program segment controls the optical head <b>14</b> to reproduce management information from the management area <b>13</b><i>c </i>in the optical disc <b>13</b>F.

A step S<b>273</b> extracts the positional information and the playback information related to a first information signal “A” from the reproduced management information. The playback information contains information representing the transfer rate Ra for the first information signal “A”. In addition, the step S<b>273</b> searches for unoccupied regions in the second areas <b>13</b><i>b </i>of the optical disc <b>13</b>F by referring to address information contained in the reproduced management information. The step S<b>273</b> decides whether or not the playback of the contents of the first information signal “A” and the recording of the contents of a second information signal “B” can be continuously and simultaneously implemented on the basis of the conditions of the unoccupied regions and the previously-indicated relation (9) or (19). The step S<b>273</b> indicates the result of the decision on the display <b>225</b>. When it is decided that the playback of the contents of the first information signal “A” and the recording of the contents of the second information signal “B” can be continuously and simultaneously implemented, the program advances from the step S<b>273</b> to a step S<b>274</b>.

The step S<b>274</b> decides whether or not the optical head <b>14</b> has reached a target position on the optical disc <b>13</b>F. Initially, the target position corresponds to first one A<b>1</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>F. When the optical head <b>14</b> has not reached the target position yet, the step S<b>274</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>274</b> to a step S<b>275</b>.

The step S<b>275</b> enables the optical head <b>14</b> to reproduce the first information signal “A” from the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>F. The step S<b>275</b> stores the reproduced first information signal “A” into the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> at the predetermined constant transfer rate Rp.

A step S<b>276</b> following the step S<b>275</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>276</b> to the step S<b>275</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>276</b> to a step S<b>277</b>.

The step S<b>277</b> transfers the first information signal “A” from the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> to the audio-video encoding and decoding unit <b>20</b> at the transfer rate Ra.

A step S<b>278</b> following the step S<b>277</b> decides whether or not the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>278</b> to the step S<b>277</b>. When the degree of occupancy of the first area <b>19</b><i>a </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>278</b> to a step S<b>279</b>.

The step S<b>279</b> forces the optical head <b>14</b> to suspend the reproduction of the first information signal “A” from the present first area <b>13</b><i>a </i>in the optical disc <b>13</b>F.

A step S<b>280</b> subsequent to the step S<b>279</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, first one B<b>1</b> of the second areas <b>13</b><i>b </i>in the optical disc <b>13</b>F. After the step S<b>280</b>, the program advances to a step S<b>281</b>.

The step S<b>281</b> decides whether or not the optical head <b>14</b> has reached the target position on the optical disc <b>13</b>F. When the optical head <b>14</b> has not reached the target position yet, the step S<b>281</b> is repeated. When the optical head <b>14</b> has reached the target position, the program advances from the step S<b>281</b> to a step S<b>282</b>.

In this way, the optical head <b>14</b> moves from the first area <b>13</b><i>a </i>to the second area <b>13</b><i>b</i>. The seek time Tab related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

The step S<b>282</b> stores the second information signal “B”, which is outputted from the audio-video encoding and decoding unit <b>20</b>, into the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> at the transfer rate Rb.

A step S<b>283</b> following the step S<b>282</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related full value yet, the program returns from the step S<b>283</b> to the step S<b>282</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related full value, the program advances from the step S<b>283</b> to a step S<b>284</b>.

The step S<b>284</b> transfers the second information signal “B” from the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> to the optical head <b>14</b> at the predetermined constant transfer rate Rp. The step S<b>284</b> enables the optical head <b>14</b> to record the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b> at the predetermined constant transfer rate Rp.

A step S<b>285</b> following the step <b>3284</b> decides whether or not the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has not reached the related empty value yet, the program returns from the step S<b>285</b> to the step S<b>284</b>. When the degree of occupancy of the second area <b>19</b><i>b </i>in the track buffer memory <b>19</b> has reached the related empty value, the program advances from the step S<b>285</b> to a step S<b>286</b>.

The step S<b>286</b> forces the optical head <b>14</b> to suspend the recording of the second information signal “B” on the present second area <b>13</b><i>b </i>in the optical disc <b>13</b>F.

A step S<b>287</b> subsequent to the step S<b>286</b> moves the optical head <b>14</b> toward a next target position. The next target position corresponds to, for example, second one A<b>2</b> of the first areas <b>13</b><i>a </i>in the optical disc <b>13</b>F. After the step S<b>287</b>, the program returns to the step S<b>274</b>.

Thus, the optical head <b>14</b> moves from the second area <b>13</b><i>b </i>to the first area <b>13</b><i>a</i>. The seek time Tba related to this movement of the optical head <b>14</b> is equal to 1.5 seconds or shorter.

During the repetitive execution of the program segment in FIG. 37, the target position of the optical head <b>14</b> is sequentially set into correspondence with the first and second areas A<b>1</b>, B<b>1</b>, A<b>2</b>, B<b>2</b>, A<b>3</b>, B<b>3</b>, . . . in the optical disc <b>13</b>F. Therefore, the optical head <b>14</b> alternately reproduces the first information signal “A” and records the second information signal “B” while accessing the first and second areas <b>13</b><i>a </i>and <b>13</b><i>b </i>of the optical disc <b>13</b> in the order as “A1, B1, A2, B2, A3, B3, . . . ”.

Preferably, the step S<b>279</b> or the step S<b>286</b> is followed by a step which decides whether or not both the reproduction of the first information signal “A” from the optical disc <b>13</b>F and the recording of the second information signal “B” thereon are required to be suspended. In this case, when both the reproduction of the first information signal “A” N from the optical disc <b>13</b>F and the recording of the second information signal “B” thereon are required to be suspended, the optical head <b>14</b> is controlled to implement the required suspension of reproduction and recording.

After the playback of the first information signal “A” from the optical disc <b>13</b>F and the recording of the second information signal “B” thereon have been completed, information representing the addresses of the second information signal “B” on the optical disc <b>13</b>F is recorded on the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F. In addition, information representing the transfer rate Rb for the second information signal “B” may be recorded on the management area <b>13</b><i>c </i>of the optical disc <b>13</b>F.

Other Features and Aspects of Embodiments

According to the basic aspects of the previously-mentioned embodiments of this invention, the signal transfer rate related to the recording and reproduction of information on and from a recording medium is fixed to the predetermined constant transfer rate Rp.

Generally, the previously-mentioned embodiments of this invention can operate on a recording medium such as a DVD-ROM, a DVD-RW, a DVD-RAM, a DVD+RW, and an HDD magnetic disc.

A DVD-ROM or a DVD-RW is subjected to CLV (constant linear velocity) control by a disc drive. Thus, the signal transfer rate is fixed throughout the whole area of the DVD-ROM or the DVD-RW.

A DVD-RAM is divided into zones. The DVD-RAM is subjected to zone CLV by a disc drive. The signal transfer rate varies from zone to zone by only several percent. The previously-mentioned embodiments of this invention are adaptable to such a slightly-varying signal transfer rate.

Regarding a DVD+RW or an HDD magnetic disc, the signal transfer rate sometimes depends on a disc radial position. The previously-mentioned embodiments of this invention can be applied to a disc area in which the signal transfer rate varies by several percent to several tens of percent.

In these case, it is preferable to calculate the signal transfer rate (Rp) regarding a recording medium as a minimum signal transfer rate which occurs when recording or reproduction is performed.

According to the previously-mentioned embodiments of this invention, information is recorded on and reproduced from two or more areas of a recording medium. The two or more areas of the recording medium may be a common area. In this case, the previously-mentioned embodiments of this invention are designed to operate in one of the following modes. During a first mode of operation, first data are reproduced from an area of a recording medium and a portion of the reproduced first data is changed to form second data, and the second data are recorded on the same area of the recording medium. During a second mode of operation, data are recorded on an area of a recording medium, and then the data are reproduced therefrom and the reproduced data are analyzed to verify whether the data have been correctly recorded on the area of the recording medium.

In the previous description of the embodiments of this invention, “seek time” taken by the optical head to move from a first disc position to a second disc position is generally equal to a time for radial head movement from a first track (a first track portion) having the first disc position to a second track (a second track portion) having the second disc position plus a rotation waiting time for which the optical head remains on or above the second track (the second track portion) until meeting the second disc position. In the case where the first and second tracks (the first and second track portions) neighbor each other, “seek time” is equal to only a rotation waiting time.